Proyectos

Author(s): J. A. Barreda-Argüeso and F. Rodríguez

Source: PHYSICAL REVIEW B 103, (2021)

Volume: 103 Pag: 085115  

Abstract: This work investigates the Ni-F distance dependence of the crystal-field (CF) transitions of Ni2+ in KNiF3 by high-pressure spectroscopy. All peaks shift to higher energy with pressure according to trends foreseen by the Tanabe-Sugano diagram. At ambient conditions, we obtain Racah and CF splitting parameters of B = 0.118 eV, 10Dq = 0.908 eV; C/B = 4.4 (10Dq/B = 7.7). B and 10Dq vary with pressure as ∂B ∂P= –0.11 meVGPa–1and ∂10Dq∂P = 24 meVGPa–1. Similar to KCoF3, the slight decrease of B with pressure reflects the strong ionic character of the Ni-F bond and its high stability against compression. We have correlated the measured pressure dependence of 10Dq with the Ni-F bond distance, showing that it follows a potential law as 10Dq = CR–n with an exponent n = 6.6 Å} 0.5, thus providing experimental data for checking the suitability of theoretical models aiming to explain the slight deviations of observed R dependencies of 10Dq from the CF theory (n = 5).We have applied the experimental 10Dq(R) relationship to determine the real Ni-F bond distances in fluoroperovskites ABF3 : Ni2+ from the spectroscopically measured 10Dq as an alternative method for determining bond distances, RNi−F, in impurity systems. We show that the so-obtained RNi−F deviates from the bond distance of the host site, RB−F, proportionally to the difference RB−F − R0, with R0 being the sum of ionic radii RF− + RNi2+ . The behavior is compared to that found for Mn2+ along the fluoroperovskite series ABF3 : Mn2+. Finally, weak UV peaks observed below the charge-transfer band gap (Eg _ 10 eV) in the absorption spectrum, the assignment of which still remains controversial, have been assigned to single and double excitation transitions. The assignment was unveiled on the basis of their energy and pressure shift.

KeyWords Plus: OPTICAL

DOI: 10.1103/PhysRevB.103.085115

Author(s): R. de la Nuez-Díaz, J. L. Arce-Diego, F. Fanjul-Vélez

Source: Proceedings Optical Interactions with Tissue and Cells XXXII; 116400D (2021)

Volume: 11640 Pag: 0

Abstract: Photodynamic therapy is a treatment technique that takes advantage of the effects induced by the body itself, together with a photosensitizer, to destroy unwanted tumor volumes with high accuracy and low invasiveness. This study analyzes treatment volume by 3D optical distributions in a realistic way from MRI images. First of all a volumetric model of a real head is built from MRI images. Optical distributions generated by the source over the tissue are considered at different brain tumor stages, and with multitude of processes that occur within the volume to be treated. By means of Monte Carlo we can estimate the photonic density that is absorbed by the tissues, whose optical properties are previously collected. This application considers that a reasonable time has passed for the photosensitizer to have reached the area under study, and that there is a minimum concentration in adjoining areas during radiation exposure. With this approach it is possible to estimate the level of radiation exposure and the affected volume. This is very relevant due to the fact that, as the radiation increases, different areas with different energy densities appear. This makes it much more complicated to apply a certain known optimal radiation on the treatment volume. A non-optimal high radiation density would damage healthy tissue, while, on the contrary, a non-optimal low radiation would not bring unwanted tissue to necrosis or apoptosis for tumor destruction, generating recurrence. This tool could be of great interest in treatment planning.

KeyWords Plus: OPTICAL

DOI: https://doi.org/10.1117/12.2578313

Author(s): José  Luis Ganoza-Quintana, Félix Fanjul-Vélez and José  Luis Arce-Diego

Source: Digital Histology by Phase Imaging Specific Biomarkers for Human Tumoral Tissues Discrimination. Appl. Sci. 2021, 11, 6142

Volume: 11640 Pag: 0

Abstract: Histology is the diagnosis gold standard. Conventional biopsy presents artifacts, delays, or human bias. Digital histology includes automation and improved diagnosis. It digitalizes microscopic images of histological samples and analyzes similar parameters. The present approach proposes the novel use of phase contrast in clinical digital histology to improve diagnosis. The use of label-free fresh tissue slices prevents processing artifacts and reduces processing time. Phase contrast parameters are implemented and calculated: the external scale, the fractal dimension, the anisotropy factor, the scattering coefficient, and the refractive index variance. Images of healthy and tumoral samples of liver, colon, and kidney are employed. A total of 252 images with 10_, 20_, and 40_ magnifications are measured. Discrimination significance between healthy and tumoral tissues is assessed statistically with ANOVA (p-value < 0.005). The analysis is made for each tissue type and for different magnifications. It shows a dependence on tissue type and image magnification. The p-value of the most significant parameters is below 10􀀀5. Liver and colon tissues present a great overlap in significant phase contrast parameters. The 10_ fractal dimension is significant for all tissue types under analysis. These results are promising for the use of phase contrast in digital histology clinical praxis

KeyWords Plus: digital histology; phase contrast imaging; biomarkers; biomedical optics; fractal analysis

DOI: https://doi.org/ 10.3390/app11136142

Author(s): Virginia Monteseguro, Vemula Venkatramu, Ulises R. Rodríguez-Mendoza  and  Victor Lavín Luis Arce-Diego

Source: Dalton Transactions

Volume: 50 Pag: 9512-9518

Abstract: The green, red, near-infrared and near-infrared-to-visible upconverted luminescence properties of Er3+/Yb3+ codoped Y3Ga5O12 nanocrystalline powders have been studied using laser spectroscopy. A diffuse reflectance and luminescence spectra confirm that Er3+ and Yb3+ ions occupy the Y3+ sites of the single-phase cubic nano-garnet. Very bright green and red luminescence of the Er3+ ions are detected by the naked eyes, even for a laser power as low as 15 mW, when the Yb3+ ions are excited at 970 nm. The red upconverted emission is more intense than that under direct excitation of the Er3+ ions. The power dependence and the dynamics of the near-infrared-to-green and near-infrared-to-red upconverted emissions show the existence of different two-photon energy transfer upconversion processes. The results here presented indicate that Er3+/Yb3+ codoped Y3Ga5O12 can be a good candidate as an optical nanoheater and nanothermometer in biomedicine applications in the first biological window.

KeyWords Plus: digital histology; phase contrast imaging; biomarkers; biomedical optics; fractal analysis

DOI: : https://doi.org/10.1039/D1DT00976A

Author(s): E. Padín-González, E. Navarro-Palomares, L. Valdivia, N. Iturrioz-Rodríguez, M. A. Correa, R. Valiente, M. L. Fanarraga

Source: Nanomedicine, Nanotechnology, Biology, and Medicinections

Volume: Pag:

Abstract: Here we propose a one-step strategy to endow nanomaterials with a custom-designed bio-identity. This study designs a universal ‘nanomaterial binding domain’ that can be genetically attached to any protein ensuring precise and spontaneous protein orientation. We demonstrate how, despite the simplicity of the method, the bioconjugation achieved: (i) is highly efficient, even in the presence of competing proteins, (ii) is stable at extreme physiological conditions (pH ranges 5.2-9.0; NaCl concentrations 0-1 M); (iii) prevents unwanted protein biofouling days after incubation in biologically-relevant conditions; and finally, (iv) avoids nanoparticle interaction with promiscuous unspecific receptors. In summary, this protein biocoating technique, applicable to a wide array of nano-designs, integrates material science and molecular biology procedures to create hybrid nanodevices with well-defined surfaces and predictable biological behaviors, opening a chapter in precision nanodiagnostics, nanosensing or nanotherapeutic applications.ological window.

KeyWords Plus: Biofouling; Biotechnology; Chimera protein; Electrostatic interaction; Nano–bio interface.

DOI: : https://doi.org/10.1016/j.nano.2020.102268

Author(s): J. A. Barreda-Argüeso, J. González, R. Valiente, T. Irifune and F. Rodríguez

Source: High Pressure Research

Volume: 40   Páginas: 117-118

Abstract: We investigated the optical properties (absorption, luminescence and Raman spectra) of nanopolycrystalline diamond (NPD) aiming at exploring its capabilities as a pressure sensor and as a pressure-cell anvil for combined X-ray/neutron and optical studies. Notably, we analysed the Raman peak shift and broadening with pressure using a Moissanite Anvil Cell (MAC). The results are compared with those obtained in a DAC, where Raman signals from NPD chips and diamond anvils strongly overlap. Its pressure behaviour in the hydrostatic and non-hydrostatic regimes were investigated. We showed that the nanopolycrystalline structure induces remarkable differences in the peak shift and broadening between NPD and natural type IIa single-crystal diamond, making NPD suitable as pressure gauge for pressure determination and testing hydrostaticity of pressure transmitting medium.

KeyWords Plus: Raman spectroscopy Luminescence Pressure gauge Pressure sensitivity Nanopolycrystalline diamond

DOI: 10.1080/08957959.2019.1702173

Author(s): C. Martín-Sánchez, A. Sánchez-Iglesias, P. Mulvaney, L. M. Liz-Marzán, and F. Rodríguez

Source: The Journal of Physical Chemistry C

Volume: 124 (16)   Páginas: 8978-8983

Abstract: The localized surface plasmon resonance (LSPR) of gold nanospheres dispersed in methanol–ethanol 4:1 was measured as a function of pressure up to 60 GPa. The LSPR exhibits an intense red-shift with pressure in the range of 0–10 GPa, followed by a slower blue-shift at higher pressures. This is because an increase in the solvent refractive index with pressure leads to a red-shift of the LSPR peak wavelength while an increase in the electron density of the gold nanospheres with pressure leads to a blue-shift. Solvent solidification at 10 GPa and associated nonhydrostatic effects have a negligible influence on the LSPR shifts in the case of nanospheres. Here we show that both the LSPR shifts and changes in the nanospheres absorption coefficient can be explained on the basis of Gans’ model, and this enables the solvent refractive index and the density of the solvent to be determined across the hydrostatic pressure range from 0 to 60 GPa. Interestingly, plasmonic sensing shows no evidence of crystallization or glass phase transitions in MeOH–EtOH 4:1 within the explored pressure range.

KeyWords Plus: Metal nanoparticles, Gold, Optical properties, Surface plasmon resonance, Solvents

Author(s): C. McMonagle, P. Comar, G. S. Nichol, D. R. Allan, J. A. Barreda-Argūeso, J. A. Gonzalez, F. Rodriguez, R. Valiente, G. Turner, E. K. Brechin and St. A. Moggach

Source: Chemical Science

Volume: 11   Páginas: 3788793-8799

Abstract: In situ single-crystal diffraction and spectroscopic techniques have been used to study a previously unreported Cu-framework bis[1-(4-pyridyl)butane-1,3-dione]copper(II) (CuPyr-I). CuPyr-I was found to exhibit high-pressure and low-temperature phase transitions, piezochromism, negative linear compressibility, and a pressure induced Jahn–Teller switch, where the switching pressure was hydrostatic media dependent.

KeyWords Plus:

DOI: https://doi.org/10.1039/D0SC03229H

Author(s): R. Valiente and F. Rodriguez

Source: JACS Applied Materials & Interfaces

Volume: 12   Páginas: 37807-37810

Abstract: In recent years, two-dimensional perovskites have received considerable attention for their potential applications for optoelectronics. Contrary to previous publications, we demonstrate that (CH₃NH₃)₂CuCl₄ hybrid organic–inorganic layered perovskite does not show any room-temperature photoluminescence (PL) under UV excitation. This statement can be extended to other perovskites with general formula AMX₃ or A₂MX₄, based on M: Cu²⁺ and X: Cl^– or Br^–. These materials, the object of increasing interest because of their efficient light absorption in a wide UV–vis–NIR range ideal for solar cells and optoelectronics, lack PL at room temperature, in contrast to recent findings reporting PL properties in this and other similar Cu²⁺-related materials.

KeyWords Plus: Absorption, Crystal structure, Solar cells, Optoelectronics, Perovskites

Author(s): C. Martín-Sánchez, S. Seibt, J. A. Barreda-Argüeso and F. Rodríguez

Source: Journal of Physics: Conference Series

Volume: 1609(1)   Páginas: 012009 (7p)

Abstract: The sensing capabilities of gold nanorods under high-pressure conditions were investigated in methanol-ethanol mixtures (up to 13 GPa) and in water (up to 9 GPa) through their optical extinction. The longitudinal SPR band of AuNR exhibits a redshift with pressure which is the result of two main competing effects: compression of the conduction electrons which increases the bulk plasma frequency (blueshift) and increase in the solvent density (redshift). The variation in de SPR peak wavelength allows us to estimate the bulk modulus of the gold nanoparticles with a precision of 10 % and to obtain analytical functions providing the pressure dependence of the refractive index of water in three phases: liquid, ice VI and ice VII. Furthermore, the SPR band shows abrupt jumps at the liquid to ice phase VI and ice phase VII transitions, which are in accordance with the first-order character of these transitions.

KeyWords Plus:

DOI: 10.1088/1742-6596/1609/1/012009

Author(s): V. Gutiérrez-Cano, R. Valiente, J.A. González, and F. Rodriguez

Source: Journal of Physics: Conference Series

Volume: 1609(1)   Páginas: 12004 (9p)

Abstract:

The optical properties of a sparsely investigated material, LaGdO3 doped with Er3+, are explored regarding its suitability as nanothermometer. Besides its excellent capabilities for dielectric applications, when doping with Er3+, this material provides a highly efficient upconversion photoluminescence (PL) for high temperature thermometry at high pressure due to its structural stability. LaGdO3 belongs to the perovskite-type ABO3 compounds with a B-type monoclinic C2/m space group (a = 14.43 Å; b = 3.69 Å; c = 9.00 Å; and β = 100.70º) at ambient conditions. It undergoes a structural phase transition to a hexagonal 𝑃3#𝑚1 phase at 3 GPa yielding a notable PL enhancement, thus enabling it as a potential high-pressure hightemperature nanothermometer.

KeyWords Plus:

DOI: doi:10.1088/1742-6596/1609/1/012004

Author(s): E. Jara, J. González, F. Aguado, R. Valiente and F. Rodríguez

Source: Journal of Physics: Conference Series

Volume: 1609(1)   Páginas: 12005 (7p)

Abstract: The effects of pressure in electronic and vibrational properties of the double perovskite CaCu3Ti4O12 have been investigated in the 0-25 GPa range by optical absorption and Raman spectroscopy. Besides a full structural characterization, we aim at unveiling whether the ambient Im3 crystal structure is stable under high pressure conditions and how its giant dielectric permitivity and electronic gap varies with pressure. Results show that there is evidence of neither structural phase transition nor metallization in CaCu3Ti4O12 in the explored pressure range. We have observed the eight Raman active modes associated with its Im3 crystal phase and obtained their corresponding frequency and pressure shift. Moreover, the direct electronic band gap (2.20 eV), which is mainly associated with the oxygen-to-copper charge transfer states, increases slightly with pressure at a rate of 13 meV GPa?1 from 0 to 10 GPa. Above this pressure is almost constant (Eg = 2.3 eV). The results highlight the high stability of the compound in its Im3 phase against compression.

KeyWords Plus:

DOI: 10.1088/1742-6596/1609/1/012005

Author(s): M. T. Candela, E. Jara, F. Aguado, R. Valiente, and F. Rodríguez

Source: Inorganic Chemistry

Volume: 124    Páginas: 22692-22703

Abstract: An experimental correlation study between the low-symmetry 3d orbital splitting pattern, Δ_e and Δ_t, determined by optical spectroscopy, and the local distortion ρ, determined by X-ray diffraction, for different Cu²⁺ and Mn³⁺ fluorides and chlorides is presented. Single crystals of different dimensionalities were explored, some of them studied under high-pressure conditions. The collection of structural and spectroscopic data provides structural correlations relating ρ and Δ_e and Δ_t in Cu²⁺ and Mn³⁺ systems, showing that Δ_e (and Δ_t) scales with ρ. Such correlations can be used to estimate local distortions of Cu²⁺ (or Mn³⁺) introduced as impurities in different chloride and fluoride host lattices from spectroscopic data. The results can be interpreted in the framework of the Jahn–Teller theory and provide support for the proposed structural scenario. The influence of the crystal anisotropy in the local structure is analyzed as well and compared with transition metal ion systems having E⊗e Jahn–Teller (Cu²⁺, Mn³⁺) and singly orbital (Ni²⁺, Mn²⁺, Fe³⁺) ground states in octahedral symmetry.

KeyWords Plus: Group theory, Crystals, Anions, Transition metals, Ions

DOI: https://doi.org/10.1021/acs.jpcc.0c07243

Autors: Félix Fanjul-Vélez, Sandra Pampín-Suárez and José  Luis Arce-Diego

Abstract: Biological tissue identification in real clinical scenarios is a relevant and unsolved medical problem, particularly in the operating room. Although it could be thought that healthy tissue identification is an immediate task, in practice there are several clinical situations that greatly impede this process. For instance, it could be challenging in open surgery in complex areas, such as the neck, where di_erent structures are quite close together, with bleeding and other artifacts a_ecting visual inspection. Solving this issue requires, on one hand, a high contrast noninvasive technique and, on the other hand, powerful classification algorithms. Regarding the technique, optical di_use reflectance spectroscopy has demonstrated such capabilities in the discrimination of tumoral and healthy biological tissues. The complex signals obtained, in the form of spectra, need to be adequately computed in order to extract relevant information for discrimination. As usual, accurate discrimination relies on massive  easurements, some of which serve as training sets for the classification algorithms. In this

work, di_use reflectance spectroscopy is proposed, implemented, and tested as a potential technique for healthy tissue discrimination. A specific setup is built and spectral measurements on several ex vivo porcine tissues are obtained. The massive data obtained are then analyzed for classification purposes. First of all, considerations about normalization, detrending and noise are taken into account.

Dimensionality reduction and tendencies extraction are also considered. Featured spectral characteristics, principal component or linear discrimination analysis are applied, as long as classification approaches based on k-nearest neighbors (k-NN), quadratic discrimination analysis (QDA) or Naïve Bayes (NB).

Relevant parameters about classification accuracy are obtained and compared, including ANOVA tests. The results show promising values of specificity and sensitivity of the technique for some classification algorithms, even over 95%, which could be relevant for clinical applications in the operating room.

Keywords: di_use reflectance spectroscopy; biological tissues; tissue classification; multiple classification

Source: Entropy, 22, 736

Doi:10.3390/e22070736

Autors: José Antonio Barreda, Jesus González. Rafael Valiente, Fernando Rodríguez

Source: Conference: 58th European High Pressure Research Group International Conference (EHPRG) September 2020, Universidad de La Laguna, Tenerife, Spain

Abstract: CsPbCl3 is considered as a structural archetype for hybrid organic-inorganic lead perovskite halides: APbX3 with A: organic cation, i.e. alkylammonium; X: Cl, Br, I [1-5]. Their enhanced optoelectronic and photovoltaic properties and the difficulty to establish structural correlations in these compouns make it the study of simple perovskites necessary. In addition, these compounds exhibit a rich structural phase-transition sequence in both inorganic and hybrid organic-inorganic perovskites that in the latter case are more complex as they are related to rotation and tioltiltinb of PbX6 octahedra induced by reorientational ordering associated with the organic cations. This structural variety becomes more intricated in nanoparticles [6-8]. Here, we present a structural correlation study in CsPbCl3: Mn2+ through the study of the band gap and the excitonic emission and Mn2+-related extrinsic emission as a function of pressure and temperature. In addition, we analyze the Raman spectrum as a structural probe and phonon study. We use single crystal of CsPbCl3: Mn2+ (1 mol%) grown by Bridgman (Orthorhombic, space group Pbm) [9]. The doping with Mn2+ acts as structure stabilizer and provides orange-red photoluminescence (PL) induced either through energy transfer from Pb2+ (band gap excitation) or by direct excitation into the Mn2+ excited states [6-8]. This characteristic makes it to exhibit both red and blue PL, the relative intensity of which can be tuned by means of different structural parameters: NC size, Mn concentration, temperature, pressure, etc. The investigation focuses on the energy variations of the band gap (Eg = 2.90 eV), exciton emission (2.83 eV) and Mn2+ PL (2.14 eV) as a function of pressure and temperature aiming to correlate those shifts with the corresponding variations of crystal volume, i.e. Pb-Cl bond distance, hence how it affects temperature energy shifts. Also, how these structural effects influence the relative exciton-to-impurity PL is the main objective of this work. The results are compared with previous high-pressure studies reported elsewhere [6-9]. Figure1: Absorption spectrum (blue) and time-resolved photoluminescence spectrum (red) of CsPbCl3: Mn2+ under excitation at 395 nm (200 kHz). The inset shows the intensity time dependence I(t) along the Mn2+ PL band.

Autors: Camino Martin-Sanchez, Ana Sanchez-Iglesias, Paul Mulvaney, Luis M Liz-Marzan, Fernando Rodriguez

Source: JOURNAL OF PHYSICAL CHEMISTRY C

DOI: 10.1021/acs.jpcc.0c01419

Abstract: The localized surface plasmon resonance (LSPR) of gold nanospheres dispersed in methanol-ethanol 4:1 was measured as a function of pressure up to 60 GPa. The LSPR exhibits an intense red-shift with pressure in the range of 0-10 GPa, followed by a slower blue-shift at higher pressures. This is because an increase in the solvent refractive index with pressure leads to a red-shift of the LSPR peak wavelength while an increase in the electron density of the gold nanospheres with pressure leads to a blue-shift. Solvent solidification at 10 GPa and associated nonhydrostatic effects have a negligible influence on the LSPR shifts in the case of nanospheres. Here we show that both the LSPR shifts and changes in the nanospheres absorption coefficient can be explained on the basis of Gans’ model, and this enables the solvent refractive index and the density of the solvent to be determined across the hydrostatic pressure range from 0 to 60 GPa. Interestingly, plasmonic sensing shows no evidence of crystallization or glass phase transitions in MeOH-EtOH 4:1 within the explored pressure range.

Autors: Ganoza Quintana, José Luis; Fanjul Vélez, Félix; Arce Diego, José Luis;

Source: XXXVIII Congreso Anual de la Sociedad Española de Ingeniería Biomédica (CASEIB)

Abstract: Los tejidos biológicos son medios turbulentos debido a que las células que los componen tienen una gran cantidad de orgánulos, tales como las mitocondrias, los ribosomas, el citoplasma, etc. Todas estas estructuras tienen diferentes índices de refracción, por tanto, estos orgánulos actúan como esparcidores en la propagación de un haz óptico incidente en un tejido biológico. La influencia de una distribución particular de esparcidores puede ser analizada por las funciones de Green. En este trabajo se introduce un parámetro de anisotropía geométrica en el espectro de potencia del tejido biológico y se estudian sus efectos sobre las estadísticas de los haces ópticos que se propagan por el mismo. Además de los efectos de otros parámetros, como la variación del índice de refracción, la pendiente del espectro de potencia y las escalas internas / externas del tejido. También se presentan algunas técnicas de obtención de estos parámetros biológicos que influyen en el modelo matemático de la propagación de la luz. ; Este trabajo ha sido parcialmente financiado por el proyecto del Plan Nacional de I+D+i “Modificación mediante alta presión de las propiedades plasmónicas y luminiscentes de nanopartículas de metales y óxidos desnudas y recubiertas” (PGC2018-101464-B-I00), del Ministerio de Ciencia, Innovación y Universidades, cofinanciado con fondos FEDER y por la Fundación San Cándido

Autors: F. Fanjul-Vélez, A. M. Díaz-Martínez, E. Garro-Martínez, and J. L. Arce-Diego

Source: OSA Technical Digest (Optical Society of America, 2019),

Abstract: Biological tissues identification is of utmost relevance in guided surgery. Nerve contrast is particularly critical, as undesired damage could cause severe collateral effects on patients. Fluorescence imaging could contribute to this aim.

DOI: https://doi.org/10.1364/FIO.2019.FTu1F.2

Author(s): V. Gutiérrez-Cano, F. Rodríguez, J. A. González, and R. Valiente

Source: PapThe Journal of Physical Chemistry C

Volume: 123 (49)    Páginas: 29818-29828

Abstract: The search of material hosts being able to incorporate Er³⁺ impurities with a thermally stable structure and high melting temperature is priority in optical thermometry. In this work, we report on the structural and spectroscopic characterization of Er³⁺–doped and Yb³⁺/Er³⁺–co-doped LaGdO₃ nanocrystals synthesized via the sol-gel Pechini method. X-ray diffraction (XRD) and Raman spectroscopy unequivocally show that the synthesis method provides nanocrystals with a single-phase B-type monoclinic structure (space group: C2/m). Intensity decay curves I(t) were measured to investigate the efficiency of upconversion processes yielding green emission. We showed that an energy transfer upconversion (ETU) process involving Yb–Er pairs governs visible emission upon NIR excitation. The temperature dependence of the thermalized green luminescence at 525 nm (²H11/2→⁴I_15/2) and 549 nm (⁴S_3/2→⁴I_15/2) was checked for thermometric applications in the RT–900 K temperature range. We demonstrate that the B-type monoclinic phase of LaGdO₃ is stable from low temperature up to 900 K. Doped with Er³⁺, it shows suitable thermometer capabilities with a maximum sensitivity of S = 4.3·10⁻³ K⁻¹ at 554 K, and a relative sensitivity decreasing from its maximum value at 0 K to S_R = 1.2 · 10⁻² K⁻¹ at 298 K. The results suggest that LaGdO₃ in its B-type monoclinic phase is a promising material as a wide-range temperature sensor, without any further surface protection.

KeyWords Plus: Luminescence, Power, Materials, Lasers, Ions

 DOI: http://dx.doi.org/10.4279/PIP.110004