Large Temperature Range Research Articles

Temperature-dependent thermoelastic properties of GaSb and InSb semiconductors: Identification through ab initio DFT simulations

III–V semiconductors are extensively used in infrared sensor applications due to their superior structural and optical properties. Due to the extremes in the manufacturing and operating temperatures of the sensors, the knowledge of temperature-dependent elastic constants of these materials is of great importance. However, reliable measurements across a large range of temperatures prove difficult due to limitations of experimental setups. Density functional theory calculations present an affordable alternative. In this work, temperature-dependent elastic properties of InSb and GaSb are investigated using density functional theory within the quasiharmonic approximation. Calculated properties relevant for operation in a wide temperature range are presented including second order elastic constants, Young’s modulus (E), shear modulus (μ), Poisson’s ratio ν and the coefficient of thermal expansion (α). Our results are compared to available experimental values and good agreement is observed.

Phase transition, thermal expansion and hygroscopicity of Fe2-2x(HfMg)xW3O12

Solid solutions Fe2-2x(HfMg)xW3O12 are synthesized to reduce the monoclinic-to-orthorhombic phase transition temperature of Fe2W3O12 and realize near zero thermal expansion over wide temperature range. The solid solutions Fe2-2x(HfMg)xW3O12 (0.3 ​≤ ​x ​≤ ​1.0) are easier to synthesize than Fe2W3O12. The X-ray diffraction and Raman analyses show that Fe2-2x(HfMg)xW3O12 adopt either a monoclinic (0.3 ​≤ ​x ​≤ ​0.5) or an orthorhombic (0.7 ​≤ ​x ​≤ ​1.0) structure at room temperature. Dilatometry measurements demonstrate that they display either low positive (x ​= ​0.3) or negative (x ​≥ ​0.5) thermal expansion above the temperature of monoclinic-to-orthorhombic phase transition or dehydration. The orthorhombic samples (0.7 ​≤ ​x ​≤ ​1.0) have intrinsically negative thermal expansion covering large temperature range involving room temperature, but are hygroscopic. Crystal water formation and releasing modify their thermal expansion property significantly. The influence of crystal water releasing process on the phonon behaviors is also observed by temperature dependent Raman spectroscopy.

Materials efficiency of electrocaloric lead scandium tantalate multilayer capacitors

Electrocaloric materials in the shape of multilayer capacitors are excellent working bodies to build cooling devices as they can exhibit large changes in temperature triggered by changes in voltage over large range of temperatures. However, high electric fields are required to drive such a large effect and yet, their efficiency has been overlooked. Here we report on the materials efficiency of lead scandium tantalate multilayer capacitors. Hence, we show that they can exchange 25 times more heat than the electrical work required to generate this heat. Besides, we observed that these multilayers capacitors are four times less efficient than lead scandium tantalate bulk ceramics for the same heat exchanged, though they exhibit a large electrocaloric effect on a much larger temperature range. Moreover, their efficiency is comparable to Gd, the prototypical magnetocaloric material. This work ultimately provides an extensive picture of the pros and cons of lead scandium tantalate.

Role of Ambient Hydrogen in HiPIMS-ITO Film during Annealing Process in a Large Temperature Range.

Indium tin oxide (ITO) thin films were prepared by high power impulse magnetron sputtering (HiPIMS) and annealed in hydrogen-containing forming gas to reduce the film resistivity. The film resistivity reduces by nearly an order of magnitude from 5.6 × 10−3 Ω·cm for the as-deposited film to the lowest value of 6.7 × 10−4 Ω·cm after annealed at 700 °C for 40 min. The role of hydrogen (H) in changing the film properties was explored and discussed in a large temperature range (300–800 °C). When annealed at a low temperature of 300–500 °C, the incorporated H atoms occupied the oxygen sites (Ho), acting as shallow donors that contribute to the increase of carrier concentration, leading to the decrease of film resistivity. When annealed at an intermediate temperature of 500–700 °C, the Ho defects are thermally unstable and decay upon annealing, leading to the reduction of carrier concentration. However, the film resistivity keeps decreasing due to the increase in carrier mobility. Meanwhile, some locally distributed metallic clusters formed due to the reduction effect of H2. When annealed at a high temperature of 700–800 °C, the metal oxide film is severely reduced and transforms to gaseous metal hydride, leading to the dramatic reduction of film thickness and carrier mobility at 750 °C and vanish of the film at 800 °C.

Deuteron nuclear magnetic resonance and dielectric studies of molecular reorientation and charge transport in succinonitrile-glutaronitrile plastic crystals

Plastic crystals are currently discussed as matrices for highly conducting materials. Among them, mixtures based on succinonitrile (SN) have received particular attention. Long ago, Austen Angell [J. Non-Cryst. Solids 131–133 (1991) 13] has shown that in mixtures with glutaronitrile (GN), the plastic phase of SN can deeply be supercooled. Here, a mixture of 60% SN – featuring deuterated methylene groups – and 40% GN is studied using 2 H nuclear magnetic resonance (NMR), thus allowing selective access to the reorientational dynamics of SN. These dynamics agree with that inferred for partially deuterated SN-GN from dielectric spectroscopy which also reveal that a significant H/D isotope effect is absent. Additionally, in the liquid and slightly below the transition to the plastically crystalline state, mixtures of 60% SN and 40% GN are studied using field-gradient NMR diffusometry as well as rotational viscometry. • Dynamics of plastic crystal from 60%-succinonitrile and 40%-glutaronitrile mixture studied over large temperature range. • Correlation times determined using deuteron NMR, dielectric spectroscopy, proton diffusometry, and viscometry. • Phase transition from liquid to plastic crystal clearly revealed by all these methods. • Time constants of protonated and deuterated mixtures agree, thus no significant H/D isotope effect. • Diffusion in the succinonitrile-glutaronitrile mixture much larger than in pure succinonitrile.

Temperature-controlled spectrophotometry: a simultaneous analysis of phase transition, thermal degradation and optical properties of semi-transparent composites from 20 °C to 450 °C.

So far, optical and effective radiative properties of polymer matrix based composites were investigated at temperatures well below their degradation temperature. At the same time, polymers exhibit temperature dependent physical properties and may undergo structural changes as their temperature raises. In this work, we employ the "Temperature-Controlled Spectrophotometry", a new method enabling to identify simultaneously phase transitions, thermal degradation and radiative properties of semi-transparent composites over a large temperature range. The method consists of measuring simultaneously the normal-normal and the normal-hemispherical transmittances and reflectances of the sample subjected to a laser irradiation with tuneable wavelength while the temperature is rised from room temperature up to 450 °C by means of a CO2 laser. Physical changes of the sample are identified from the temperature variation of normal-normal transmittance and specular reflectance measurements. Most of the results here are presented at a specific wavelength of 1070 nm but the proposed method is suitable over the semi-transparency spectral domain of the material by changing the wavelength of the probe laser. An inverse method for parameter identification based on normal-hemispherical measurements is employed to determine the transport effective radiative properties of the sample, namely the transport extinction coefficient and the transport scattering albedo from room temperature to 325 °C.

300 mm CMOS-compatible fabrication of Ru2Si3 sub-50 nm thin films and characterization

We report the thermoelectric characterization of Ru2Si3 thin films. Ruthenium (VI)-silicide was formed via silicidation by rapid thermal processing of ruthenium on amorphous, undoped silicon of different thicknesses (sub-50 nm). 300 mm wafer level processes were applied, utilizing physical and chemical vapor deposition methods. High-temperature-XRD, energy dispersive x-ray spectroscopy, transmission electron microscopy, and time-of-flight secondary ion mass spectrometry confirm the formation of single-phase Ru2Si3 thin films. Thermoelectric measurements reveal exceptionally high Seebeck coefficients of up to 1.5 mV/K close to room temperature in dependence of adjustable oxide nanoskins. Due to the thermal stability of the nanoskins, fine-tuning of the thermoelectric properties by rapid thermal processing could be applied in a large temperature range.

Boosting the Electrocatalytic Oxygen Evolution of Perovskite LaCo1- x Fex O3 by the Construction of Yolk-Shell Nanostructures and Electronic Modulation.

Realizing the rational design of perovskite oxides with controllable compositions and nanostructures remains a tremendous challenge for the development of efficient electrocatalysts. Herein, a ligand-assisted synthetic strategy to fabricate perovskite oxidesLaCo1- x Fex O3 with yolk-shell nanostructures is developed. Benefiting from the unique structural and compositional merits, LaCo0.75 Fe0.25 O3 exhibits an overpotential of 310mV at a current density of 10mAcm-2 and long-term stability of 100 h for the oxygen evolution reaction. In situ Raman spectroscopy demonstrates that Fe substitution facilitates the pre-oxidation of Co sites and induces the surface reconstruction into active Co oxyhydroxides at a relatively lower applied potential, guaranteeing excellent catalytic performances. Density functional theory calculations unravel that the appropriate introduction of Fe into perovskite LaCoO3 leads to the improved electroactivity and durability of the catalyst for the oxygen evolution reaction (OER). Fe-3d orbitals show a pinning effect on Co-3d orbitals to maintain the stable valence state of Co sites at the low overpotential of the OER. Furthermore, Zn-air batteries (ZABs) assembled with LaCo0.75 Fe0.25 O3 display a high open circuit potential of 1.47V, superior energy density of 905Whkg-1 Zn , and excellent stability in a large temperature range. This work supplies novel insights into the future developments of perovskite-based electrocatalysts.

Solid electrolyte based on 2-adamantanone for all-solid-state lithium-ion batteries

Solid-state batteries are considered the next step in battery technology. Materials investigated for application as solid-state electrolytes are mainly oxide ceramics, sulfidic (glass-) ceramics, and polymers. Besides these, another class of solid electrolytes with promising properties is based on plastic crystals. Especially due to their waxy behavior, they promise good interfaces within a solid-state battery. In this work, a new plastic crystal, 2-adamantanone, is investigated as basis for a solid electrolyte for the first time. Its large temperature window from − 95 to 255 °C for its plastic (conductive) state and the high dipole moment of 3.4 D make it a promising material for battery application. The mixture with a lithium salt was investigated thermally with TGA and DSC revealing stability in a large temperature range from − 30 to + 80 °C. IR investigations show the dissociation of the conductive salt, which is necessary for the lithium ion conduction. The ionic conductivity of the electrolytes reaches values up to 1.4·10−4 S/cm at room temperature with a very low activation energy of only 0.32 eV.

Neural Network Modeling of NiTiHf Shape Memory Alloy Transformation Temperatures

Data-driven techniques are used to predict the transformation temperatures (TTs) of NiTiHf shape memory alloy. A machine learning (ML) approach is used to overcome the high-dimensional dependency of NiTiHf TTs on numerous factors, as well as the lack of fully known governing physics. The elemental composition, thermal treatments, and post-processing steps that are commonly used to process NiTiHf and have an impact on the material phase transitions are used as input parameters of the neural network model (NN) to design the TTs. Such a feature selection led to the use of most of the accessible information in the literature on NiTiHf TTs, as all processing features required to be fed into the NN model. Considering most of the regular NiTiHf processing factors also enables the option of tuning additional characteristics of NiTiHf in addition to the TTs. The work is unique as all the four main TTs and their associated peak transformation temperatures are predicted to have complete control over the material phase change thresholds. Since 1995, extensive experimental research has been conducted to design NiTiHf TTs with a large temperature range of around 800 °C, paving the path for the current work’s ML algorithms to be fed. A thorough data collection is created using both unpublished data and available literature and then analyzed to select twenty input parameters to feed the NN model. To forecast the NiTiHf TTs, a total of 173 data points were gathered, verified, and selected. The model's overall determination factor (R2) was 0.96, suggesting the viability of the proposed NN model in demonstrating the link between material composition and processing factors, as well as identifying the TTs of NiTiHf alloy. The effort additionally validates the generated results against existing data in the literature. The validation confirms the significance of the proposed model.

Temperature and Temperature Stress Analysis in Mass Concrete under Cold Environments of Strong Wind and Large Diurnal Temperature Range

Special environmental condition with strong wind and large diurnal temperature range is not conducive for the control of crack development during the curing of mass concrete in the cold environment of Northwest China. In this study, the temperature at four measured points along the vertical profile of a mass concrete was measured over 14 days. Then, a thermal-mechanical model with the optimized initial condition, thermal parameters, boundary conditions, and the effects of rebar on temperature stress of concrete was built. Based on the observations and numerical model, the effects of environmental factor on the peak temperature, temperature fluctuation amplitude, and maximum temperature stress of the mass concrete are analyzed. The result showed that increasing wind speed can reduce the temperature of the concrete, but an opposite result is observed with increase in diurnal temperature range. Moreover, the more obvious diurnal variation of concrete temperature with the increase in wind speed and diurnal temperature range is not conducive to the thermal stability of the structure, especially for horizontal and side surfaces. Accordingly, increasing wind speed and diurnal temperature range will increase the peak temperature stress of the concrete and the overall stress level. Strong wind and large diurnal temperature range significantly increase the temperature stress and its duration for the side surface. The high temperature stress and intensive daily variation of temperature stress at the horizontal surface affect the durability of the concrete material. Therefore, the temperature stresses of the horizontal surface under wind speed levels 3, 4, 5, and 1.25 times large diurnal temperature range easily exceed the tensile strength; then, the temperature crack will appear. Combined with the research results, the temperature control and crack prevention measures are proposed under the condition of ensuring concrete strength. The study will further guide the improvement and optimization of mass concrete construction in an extreme environment.

Nickel isotope fractionation in komatiites and associated sulfides in the hart deposit, Late Archean Abitibi Greenstone Belt, Canada

Extremely light and highly variable δ60Ni values have been observed in komatiite-associated magmatic sulfides in recent studies. In this study, we examine the mechanisms of Ni isotope fractionation between silicate and sulfide liquids in the Hart komatiite-associated Fe-Ni-Cu-sulfide system. We assess the petrogenetic significance of these mechanisms using Ni isotope and concentration data. The concentration of Ni in bulk rock varies from 774 to 2690 ppm in komatiite samples with no sulfide minerals to 8380–39,300 ppm in samples almost entirely consisting of sulfide minerals. The δ60Ni values vary from +0.14‰ in komatiite samples with no sulfide minerals to −1.06‰ in samples dominantly consisting of sulfide minerals. A theoretical model of fractionation between the komatiitic lava and sulfide xenomelt with nickel isotope exchange followed by fractional crystallization during crystallization of the sulfide melt can produce a range of δ60Ni values from +0.17‰ to −1.02‰ in sulfide-rich rocks depending on the extent of fractional crystallization and the amount of trapped melt between the sulfide mineral grains, which corresponds well with the range of values observed in these rocks. This proposed model requires fractionation of Ni isotopes between sulfide liquid and the earliest formed sulfide crystals during crystallization. Effects of later crystallization during peritectic reactions and subsolidus exsolution could be tested by in situ measurements of Ni isotopes in different textural varieties of pentlandite that formed over a large range of temperatures during cooling.

Molecular dynamics of alkyl benzoate liquid crystals in the bulk state and in the surface layer of their composites with oxide nanopowders

This paper presents the results concerning monotropic nematic liquid crystals 4-pentylphenyl 4′-alkyl benzoate (5PnB) (n = 3 or 5 carbon atoms in the alkyl chain). Their mesophase properties were supported by images of the polarized optical microscopy. Molecular dynamics in the bulk samples or in the composites prepared with aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range, appropriately chosen. Thermo gravimetric and infrared investigations were additionally performed. The data were compared with those of structurally related nematics like cyanophenyl pentyl benzoates, which have a cyan group instead of the pentyl chain. The dielectric spectra of the bulk 3P5B and 5P5B demonstrate a dielectric behavior with several relaxation processes as expected for nematic liquid crystals. The temperature dependence of the relaxation rates (and of the dielectric strength) seems to have two distinguished regimes. Thus, in the isotropic state, at higher temperatures the data obey the Vogel–Fulcher–Tammann law, whereas an Arrhenius law is fitted at lower temperature, in a close similarity to the behavior of a constrained dynamic glass transition. Samples with a high density of silica (larger than 7 g aerosil/1 g of 5PnB) were prepared to observe a thin layer adsorbed on the particle surface; it was estimated that almost each guest 5PnB molecule interacts with the aerosil surface. For the composites only one main relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in the surface layer. Infrared spectroscopy shows that these molecules interact with the surface by the ester carbonyl group leading to the monolayer self-assembly at liquid–solid interface. We note once more the importance of the functional unit(s) for the interaction with the hydroxyl groups on the aerosil surface.

Multiaxial Molecular Ferroelectrics with a Large Viable Temperature Range

Multiaxial Molecular Ferroelectrics with a Large Viable Temperature Range

Production features of duckweed (Lemna L.) as an object of cultivation in integrated technologies

The issues of exploitation of duckweed communities, selection of the most promising species from the genus duckweed and determination of its productivity in the second zone of fish farming are considered. Duckweed is an aquatic, free-floating or submerged, mostly perennial higher plants, distributed throughout the Earth, with the exception of hot dry deserts and cold polar regions. Duckweed can withstand a large temperature range, from heat to frost, light-loving. It contains (in terms of dry matter): 20–38% protein, up to 5% fat, fiber, vitamins A, C and group B, anthocyanins, triterpene compounds, as well as iodine, iron, biogens, calcium, silicon, magnesium, heavy metals, trace elements. The experiments were carried out at the experimental production base of VNIIR in fiberglass baths of 6.0×0.7×0.6 m in the period from June 6 to the end of August, and observations of the state of the duckweed biotope in a reservoir with an area of 60 acres and an average depth of 1.6 m from the end of April to the third decade of September, The results obtained during the research allow us to conclude that the exploitation of duckweed biotopes (Lemna minor L.) in the second zone of fish farming has good prospects, which is expressed in obtaining about 50 tons/ha or more of biomass in raw form during the growing season. This makes it possible to create a raw material base for the production of duckweed feed and feed additives in the form of flour, powder, granulate, pastes, etc.

High-precision calibration for strain and temperature sensitivities of Rayleigh-scattering-based DOFS at cryogenic temperatures

Under extreme conditions such as cryogenic temperatures, the application of optical fiber sensors inevitably encounters significant challenges, which include the calibrations associated with the thermal problems of sensor placement and heat sinking and the nonlinear dependence of cryogenic temperatures. Thus, fundamental investigations involving high-precision calibrations of the strain and temperature at cryogenic temperatures are essential. To this end, in this study, the thermo-optic coefficient, temperature and strain sensitivity coefficients for a Rayleigh-scattering-based distributed optical fiber sensor (DOFS) were calibrated. This experiment was implemented using a self-built low-temperature test device, and the calibration study was conducted over a large cryogenic temperature range, from 77 K to room temperature. The results indicated that the strain sensitivity coefficient of the Rayleigh-scattering-based DOFS is temperature-independent, whereas the temperature sensitivity coefficient has a significantly nonlinear temperature dependence and is associated with the coating polymer layers of the fiber. The coefficients and fitting functions were obtained over a large range of cryogenic temperatures, which indicated the invaluable properties of optical fibers in practice. Furthermore, the strain and temperature of an aluminum beam under thermal and bending loads were measured. The results indicated good agreement between the optical fibers and strain gauges, which verified the availability and reliability of Rayleigh-scattering-based distributed optical fibers in cryogenic environments.

Carbon dioxide solubility in Deep Eutectic Solvents: Modelling using Cubic Plus Association and Peng-Robinson equations of state

Carbon Dioxide (CO2) is the greenhouse gas that most contributes to global warming and climate change due to fossil fuels combustion, transportation, and other industrial process. Carbon capture, storage, and utilization (CCSU) is an effective method to reduce CO2 emission. Chemical absorption is the most straightforward technology for post-combustion CO2, and monoethanolamine (MEA) has been proved to be the most efficient chemical solvent. However, MEA is not environment friend, thus indicating the need for developing eco-friendly absorbers for CO2 capture, such as Deep Eutectic Solvents (DESs). Despite recent experimental studies investigating CO2 solubility in DESs, thermodynamic modelling is important to understand the system behavior. Thus, this study modelled CO2 solubility in thirteen DESs found in a large range of temperature (from 303.15 to 343.15 K) and pressure range (from 0.06 to 12 MPa). Cubic-Plus Association (CPA) and Peng-Robinson 78 equations of state were used to compare efficiency. The results indicate that fitting the binary interaction parameter (kij) promotes a better reproduction result than considering kij equals zero. Despite all association schemes of CO2 providing accurate results, the 4 C association scheme (two electron acceptors and two electron donors) resulted in better equilibrium description. Both models describe experimental data very well, yet the individual component approach presents better results than pseudo-component approach, corroborating with DESs definition.

The Gaia-ESO Survey: The analysis of the hot-star spectra

Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey that has collected, over a period of six years, spectra of ~105 stars. This survey provides not only the reduced spectra, but also the stellar parameters and abundances resulting from the analysis of the spectra. Aims. The GES dataflow is organised in 19 working groups. Working group 13 (WG13) is responsible for the spectral analysis of the hottest stars (O, B, and A type, with a formal cutoff of Teff > 7000 K) that were observed as part of GES. We present the procedures and techniques that have been applied to the reduced spectra in order to determine the stellar parameters and abundances of these stars. Methods. The procedure used was similar to that of other working groups in GES. A number of groups (called Nodes) each independently analyse the spectra via state-of-the-art techniques and codes. Specific for the analysis in WG13 was the large temperature range covered (Teff ≈ 7000–50 000 K), requiring the use of different analysis codes. Most Nodes could therefore only handle part of the data. Quality checks were applied to the results of these Nodes by comparing them to benchmark stars, and by comparing them to one another. For each star the Node values were then homogenised into a single result: the recommended parameters and abundances. Results. Eight Nodes each analysed part of the data. In total 17 693 spectra of 6462 stars were analysed, most of them in 37 open star clusters. The homogenisation led to stellar parameters for 5584 stars. Abundances were determined for a more limited number of stars. The elements studied are He, C, N, O, Ne, Mg, Al, Si, and Sc. Abundances for at least one of these elements were determined for 292 stars. Conclusions. The hot-star data analysed here, as well as the GES data in general, will be of considerable use in future studies of stellar evolution and open clusters.

Lattice Dynamics and Structural Phase Transitions in Two-Dimensional Ferroelectric Methylhydrazinium Lead Bromide Investigated Using Raman and IR Spectroscopy

Two-dimensional (2D) lead halide perovskites are promising photovoltaic, light-emitting, nonlinear optical, and ferroelectric materials. Their key optoelectronic properties and polar order of organic cations are strongly affected by the dynamic response of the ionic lattice. Herein, we report polarized Raman and IR spectroscopy studies of methylhydrazinium lead bromide (MHy2PbBr4) exhibiting ferroelectric, photoluminescence, and multiple nonlinear optical phenomena. We determined the wavenumbers of longitudinal optical (LO) and transverse optical (TO) modes and their symmetries. These studies reveal that the dielectric response of MHy2PbBr4 is dominated by vibrations of the inorganic sublattice, which exhibits a large LO-–TO splitting (up to 44 cm–1). We also performed temperature-dependent Raman spectroscopy studies to monitor the effect of temperature on lattice dynamics and the effect of structural phase transitions on phonon modes. Raman spectroscopy data reveal that Raman bands are very narrow at 80 K, indicating a well-ordered structure. However, the increase of temperature leads to a very pronounced broadening of bands, indicative of a strong increase of lattice anharmonicity due to increased motional freedom of MHy+ cations and the inorganic network. Although former X-ray diffraction analysis showed that MHy2PbBr4 undergoes an order–disorder phase transition at 351 K, this transition leads to weak wavenumber shifts and broadening of Raman bands, more pronounced for modes related to the inorganic subnetwork. Furthermore, we do not observe any clear anomalies at 371 K, where the second phase transition into another disordered phase occurs. Our results indicate, therefore, that in contrast to many 2D lead halide perovskites, the dynamics of MHy+ cations and the inorganic network in MHy2PbBr4 do not exhibit pronounced slowing down at the order–disorder phase transition temperature but rather decrease gradually over a very large temperature range.

Photonic and Optomechanical Thermometry

Temperature is one of the most relevant physical quantities that affects almost all processes in nature. However, the realization of accurate temperature standards using current temperature references, like the triple point of water, is difficult due to the requirements on material purity and stability of the environment. In addition, in harsh environments, current temperature sensors with electrical readout, like platinum resistors, are difficult to implement, urging the development of optical temperature sensors. In 2018, the European consortium Photoquant, consisting of metrological institutes and academic partners, started investigating new temperature standards for self-calibrated, embedded optomechanical sensor applications, as well as optimised high resolution and high reliability photonic sensors, to measure temperature at the nano and meso-scales and as a possible replacement for the standard platinum resistant thermometers. This article presents an overview of the results obtained with sensor prototypes that exploit photonic and optomechanical techniques for sensing temperatures over a large temperature range (5 K to 300 K). Different concepts are demonstrated, including ring resonators, ladder-like resonators and suspended membrane optomechanical thermometers, highlighting initial performance and challenges, like self-heating that need to be overcome to realize photonic and optomechanical thermometry applications.