Thermal conductivity of Na<Subscript>2</Subscript>W<Subscript>2</Subscript>O<Subscript>7</Subscript> crystal

The thermal conductivity of Na₂W₂O₇ single crystal has been studied along the main crystallographic directions at temperatures of 50–573 K. A low thermal conductivity is found to correlate with a significant difference in the cation weight.     

Spin glass and glass-like lattice behaviour in HoB66 at low temperatures

The low-temperature specific heat, magnetic susceptibility, and thermal expansion are studied experimentally in the fcc boride HoB₆₆ and compared to similar quantities in non-magnetic LuB₆₆. The anomalous behaviour observed in HoB₆₆ is explained within a glass-like picture together with magnetic subsystem ordering processes. The character of the observed anomalies suggests the existence of a spin-glass phase transition in HoB₆₆ below a characteristic temperature of T _s ?≈?0.98?K.     

Thermal conductivity and heat capacity of a ZnWO<Subscript>4</Subscript> crystal

The thermal conductivity of a ZnWO₄ single crystal in the principal crystallographic directions has been studied experimentally in the temperature range of 50–573 K, and the heat capacity of the single crystal has been measured in the range of 81–301 K.     

Thermal expansion of dysprosium tetraboride

The temperature variations of the interplanar spacings a(T) and c(T) in the crystal lattice of dysprosium tetraboride have been studied using X-ray diffraction in the temperature range 5?C300 K. Anomalous variations of a(T) and c(T) in the temperature range of magnetic transformations, anisotropy of the thermal expansion of DyB₄, and the monoclinic distortion of the crystal structure at low temperatures have been revealed. The magnitudes of the spontaneous magnetostriction, the thermal expansion coefficients ??a and ??c, and the exchange integrals Y _a and Y _c have been determined.     

Heat capacity and thermal expansion of icosahedral lutetium boride LuB66

The experimental values of heat capacity and thermal expansion for lutetium boride LuB₆₆ in the temperature range of 2–300 K were analysed in the Debye–Einstein approximation. It was found that the vibration of the boron sub-lattice can be considered within the Debye model with high characteristic temperatures; low-frequency vibration of weakly connected metal atoms is described by the Einstein model.     

Defect mode and crystal-electric-field effects on the thermal expansion and heat capacity of RB<Subscript>50</Subscript> boride

This study aimed to evaluate the suitability of using unfired and fired pumice as cement replacement materials as well as their effect on the thermal resistance of hardened ordinary Portland cement (OPC) pastes. Different OPC–pumice (unfired and fired) blends were prepared by partial replacement of OPC by 0, 10 and 20 of pumice (mass%). The effect of the addition of 1 and 5 % of active alumina on the mechanical properties and thermal resistance of different OPC–pumice (unfired) blends was investigated. The fire resistance test was done by exposing the hardened blended cement cubes to elevated temperatures of 200, 400, 600 and 800 °C for 3 h and allowed them to cool down to room temperature before testing for their mechanical properties. The phase composition and thermal analysis of some selected specimens were investigated by XRD, DSC and DTA/TG techniques. The obtained results indicated that replacing OPC by 10 and 20 % by pumice (unfired and fired) improved its thermal stability at different firing temperatures. The cement blend prepared by replacement of OPC with 10 % pumice showed the highest fire resistance. The addition of 1 and 5 % of alumina (A) to OPC–pumice blends causes a notable improve in their mechanical properties and thermal resistance.     

Anharmonicity of Lattice Vibrations and the Thermal Properties of Cd1 – xSrxF2 Solid Solutions

Physics of the Solid State - The temperature changes in the crystal lattice parameters a(T) of cadmium and strontium fluorides and also of their mutual Cd1&nbsp;–&nbsp;xSrxF2 (x =...     

Thermal properties of TbB4

This paper presents the results of an experimental study of the temperature dependencies of the heat capacity and the lattice parameters of terbium tetraboride (TbB₄) measured in a temperature range of 2–300 K. This study reveals the anomalies of the above characteristics of TbB₄ at the temperatures of the corresponding magnetic phase transitions (Neel points) T _N1 = 44 K and T _N2 = 24 K. The transitions of TbB₄ from the tetragonal crystalline structure into the orthorhombic one at temperatures below T _N1 were identified. Within our experimental accuracy, no structural transition into the orthorhombic symmetry at temperatures above 80 K was observed. The individual temperature variations of lattice-related and magnetically induced components of the measured properties of TbB₄ are extracted using the data for the diamagnetic LuB₄. As a result, separate contributions of lattice and magnetic subsystems of TbB₄ are determined.     

Thermal expansion and lattice dynamics of RB66 compounds at low temperatures

Thermal characteristics of the phonon and magnon subsystems of icosahedral borides RB₆₆ (R = Gd, Tb, Dy, Ho, Eu, or Lu) have been studied based on the obtained experimental data on the thermal expansion of the borides and the earlier results on their heat capacity in the range of 2–300 K. The contribution to the expansion of borides containing paramagnetic R ³⁺ ions, which is characteristic of transition to the spin-glass state, has been revealed. The phonon spectrum moments of RB₆₆ compounds and the Grüneisen parameters have been calculated.