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The standard molar enthalpies of formation of PbBi12O19(s) and ϕ-Pb5Bi8O17(s) at 298.15 K were determined using an isoperibol calorimeter. The enthalpies of solution of ternary compounds, namely, PbBi12O19(s) and ϕ-Pb5Bi8O17(s) as well as stoichiometric oxide mixtures, namely, {PbO(s) + 6 Bi2O3(s)} and {5 PbO(s) + 4 Bi2O3(s)} in HNO3 (aq., 4.47 mol kg−1) at T = 298.15 K were measured. Using these values, Δ f H m o (298.15 K) of PbBi12O19(s) and ϕ-Pb5Bi8O17(s) were determined as (-3549.6 ± 23.8) kJ mol−1 and (-3239.4 ± 7.6) kJ mol−1, respectively. The given uncertainties were calculated as 2σ of the mean with 0.95 level of confidence.

Flower-like ammonium cadmium phosphate monohydrate was synthesized by solid-state reaction at low temperature and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, and elemental analysis. The product NH4CdPO4·H2O was obtained with flower-like morphology by the addition of fatty alcohol-polyoxyethylene ether surface-active agent. Based on Hess’s law, thermochemical cycle was designed to determine the dissolution enthalpies of reactants and products using a solution-reaction isoperibol calorimeter at 298.15 K, and the molar reaction enthalpy was calculated on the basis of above dissolution enthalpies. With the aid of other auxiliary thermodynamic data, the standard molar formation enthalpy of the title compounds was concluded: $$ \Updelta_{\text{f}} H_{\text{m}}^{-\!\!\!\!\circ} [{\text{NH}}_{4} {\text{CdPO}}_{4} \cdot {\text{H}}_{2} {\text{O}}] = ( - 1749.82 \pm 0.76)\; {\text{kJ}}\; {\text{mol}}^{ - 1} . $$

The standard molar reaction enthalpies of two reactions, CeCl3 · 7H2O(s) + 3CCl3COOH(s) = Ce(TCA)3· 3H2O(s) +3HCl(g) + 4H2O(1) (1) and Ce(TCA)3· 3H2O (s) + 2C9H7NO (S) = Ce(TCA) (C9H6NO)2 (s) + 2CCl3COOH(s) + 3H2O(1) (2), were investigated by classical solution calorimetry and an isoperibol calorimeter at 298.15 K. The standard molar enthalpies ΔsH·m of solution of CeCl3 · 7H2O(s), 3CCl3COOH(s), Ce(TCA)3 · 3H2O(s), Ce(TCA)3 · 3H2O(s), 2C9H7NO(s), Ce-(TCA) (C9H6NO)2(s) and 2CCl3COOH(s) were determined to be (50.615 ± 0.028), (23.431 ± 0.027), (94.206 ± 0.010), (54.151 ± 0.020), (27.485 ± 0.045), (106.392 ± 0.060) and-(14.893 ± 0.026) kJ/mol, respectively. The reaction enthalpies ΔrH⊖m of reactions (1) and (2) were obtained to be (204.279 ± 0.023) and-(9.863 ± 0.041) kJ/mol, respectively. According to the above results and the data given in literature, through Hess' law, the standard molar enthalpies ΔtH⊖m of formation of Ce(TCA)3 ± 3H2O(s) and Ce(TCA)(C9H6NO)2 (s) were estimated to be-(3060.0 ± 0.087) and-(1369.0 ± 0.292) kJ/mol, respectively.

The two complexes, [Ln(Ala)2(Im)(H2O)](ClO4)3 (Ln=Pr, Gd), were synthesized and characterized. Using a solution-reaction isoperibol calorimeter, standard enthalpies of reaction of two reactions: LnCl3⋅6H2O(s)+2Ala(s)+Im(s)+3NaClO4(s)=[Ln(Ala)2(Im)(H2O)](ClO4)3(s)+3NaCl(s)+5H2O(l) (Ln=Pr, Gd), at T=298.15 K, were determined to be (39.26±0.10) and (5.33±0.12) kJ mol–1 , respectively. Standard enthalpies of formation of the two complexes at T=298.15 K, ΔfHΘm {[Ln(Ala)2(Im)(H2O)](ClO4)3(s)} (Ln=Pr, Gd), were calculated as –(2424.2±3.3) and –(2443.4±3.3) kJ mol–1 , respectively.

Lanthanum tellurites, La2Te3O9 and La2Te4O11, have been prepared by the solid state synthesis route and characterized for their phase and chemical compositions by XRD and ICP-AES analyses. The molar enthalpies of solution of La2Te3O9(s), La2Te4O11(s), La2O3(s) and TeO2(s) in 0.150 dm3 of 10.98 mol dm−3 HCl were measured using an isoperibol calorimeter. From these results and other auxiliary data the standard molar enthalpy of formation of La2Te3O9(s) and La2Te4O11(s) were derived to be (−2814.6 ± 12.9) kJ mol−1 and (−3116.5 ± 17.3) kJ mol−1, respectively, at 298.15 K which are the first reported thermodynamic data on these compounds at 298.15 K.

The crystals of four complexes of rare earth perchlorate with dl -α-alanine and imidazole were synthesized and characterized. The components of them were determined to be [RE(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (RE: Sm, Eu, Dy, Er) by FT-IR, chemical, elemental and thermal analysis. The enthalpies of dissolution of [2C 3 H 7 NO 2 (s) + 3NaClO 4 (s)], [C 3 H 4 N 2 (s) + RECl 3 ·6H 2 O(s)] and [3NaCl(s)], {[RE(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (s)} were determined by a solution–reaction isoperibol calorimeter at T =298.15 K, respectively. According to Hess’s law, the standard molar enthalpies of reaction of four reactions, RECl 3 ·6H 2 O(s) + 2C 3 H 7 NO 2 (s) + C 3 H 4 N 2 (s) + 3NaCl(s) = [RE(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (s) + 3NaCl(s) + 5H 2 O(l) (RE: Sm, Eu, Dy, Er) were determined to be 4.87±0.20, 7.23±0.19, 0.96±0.27 and 12.88±0.32 kJ mol −1 , respectively. The standard molar enthalpies of formation of the four complexes at T =298.15 K, Δ f H m Θ {[Re(C 3 H 7 NO 2 ) 2 (C 3 H 4 N 2 )(H 2 O)](ClO 4 ) 3 (s)} (RE: Sm, Eu, Dy, Er), were determined to be −(2448.1±3.3), −(2360.3±3.3), −(2451.8±3.3) and −(2444.3±3.3) kJ mol −1 , respectively.

Using an on-line solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction: LnCl3·6H2O(s) + 2C9H7NO(s) + CH3COONa(s) = Ln(C9H6NO)2(C2H3O2)(s) + NaCl(s) + 2HCl(g) + 6H2O(l) (Ln: Nd, Sm), were determined at T=298.15 K, as −(56.9±1.4) and −(67.9±1.5) kJ mol−l, respectively. From the mentioned standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of Ln(C9H6NO)2(C2H3O2)(s) (Ln: Nd, Sm), at T=298.15 K, have been derived to be: −(1494.7±3.3) and −(1501.5±3.4) kJ mol−l, respectively.

Crystals of two coordination compounds of rare earth chlorides with glycine, [Ln(Gly)3(H2O)2]Cl3·2H2O (Ln = Pr, Nd; Gly = glycine), were prepared and characterized. Using a solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction, LnCl3·6H2O(s) + 3Gly(s) = [Ln(Gly)3(H2O)2]Cl3·2H2O(cr) + 2H2O(l) (Ln = Pr, Nd; Gly = glycine), were determined at T = 298.15 K, as (19.2 ± 0.4) kJ·mol-l and (63.4 ± 0.5) kJ·mol-l, respectively. From the above standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of [Ln(Gly)3(H2O)2]Cl3·2H2O (Ln = Pr, Nd; Gly = glycine), at T = 298.15 K, have been derived to be −(3875.7 ± 1.1) kJ·mol-l and −(3825.2 ± 1.1) kJ·mol-l, respectively.

The following reactions 2 Zn ( Ac ) 2 ·2 H 2 O ( s )+ H 5 IO 6 ( s )→ Zn 2 HIO 6 ·1.25 H 2 O ( s )+4 HAc ( l )+2.75 H 2 O ( l ) 2 Cd ( Ac ) 2 ·2 H 2 O ( s )+ H 5 IO 6 ( s )→ Cd 2 HIO 6 ·1.25 H 2 O ( s )+4 HAc ( l )+1.25 H 2 O ( l ) 2 Cu ( Ac ) 2 · H 2 O ( s )+ H 5 IO 6 ( s )→ Cu 2 HIO 6 ·2 H 2 O ( s )+4 HAc ( l ) have been studied. The molar dissolution enthalpies of the reactants and products in a certain solvent (3 M l −1 HNO 3 ) of this three reaction have been measured using an isoperibol calorimeter at 298 K. From these values, combined with auxiliary values, the standard molar formation enthalpies of Zn 2 HIO 6 ·1.25H 2 O (s), (298.2 K), Cd 2 HIO 6 ·1.25 H 2 O (s), (298.2 K) and Cu 2 HIO 6 ·2H 2 O (s), (298.2 K) have been determined to be Δ f H m θ (Zn 2 HIO 6 ·1.25 H 2 O (s), 298.2 K) = −1342.11 kJ mol −1 , Δ f H m θ (Cd 2 HIO 6 ·1.25H 2 O (s), 298.2 K) = −1405.49 kJ mol −1 and Δ f H m θ (Cu 2 HIO 6 ·2H 2 O (s), 298.2 K) = −1226.08 kJ mol −1 .

The molar enthalpies of solution of SrTeO3, SrTe2O5, TeO2, and SrCO3in HCl (aq,c=11 mol·dm−3) have been measured by using an isoperibol calorimeter. From these results and other auxiliary data, the standard molar enthalpies of formation ΔfHm°(298.15 K) of SrTeO3(cr) and SrTe2O5(cr) have been calculated to be −(1026.0±10.7) kJ·mol−1and −(1381.2±12.9) kJ·mol−1, respectively. These values of enthalpies of formation are consistent with the second-law enthalpies of formation derived from their vapour pressures determined in this laboratory by a transpiration technique.

The molar enthalpies of solution of CaTeO3, CaTe2O5, TeO2, and CaCO3in HCl(aq,c=11 mol·dm−3) have been measured by using an isoperibol calorimeter. From these results and other auxillary data, the standard molar enthalpies of formation ΔfHm°(298.15 K) of CaTeO3(s) and CaTe2O5(s) have been calculated to be −(985.4±4.8) kJ·mol−1and −(1337.4±7.2) kJ·mol−1, respectively. These values are consistent with the second law enthalpies of formation of the compounds determined in this laboratory by a transpiration technique.

The molar enthalpies of solution of ZrTe 3 O 8 , TeO 2 , and ZrF 4 , in HF(aq) of concentration 10 mol.dm −3 have been measured using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar enthalpy of formation of ZrTe 3 O 8 (s) has been determined to be Δ f H m °(298.15 K) = −(2119.2 ± 9.6)kJ·mol −1 .

Four compounds in the system Li 2 O-MoO 3 , namely, Li 2 MoO 4 (c), Li 2 Mo 2 O 7 (c), Li 2 Mo 3 O 10 (c) and Li 2 Mo 4 O 13 (c) were synthesized and characterized by both chemical and X-ray diffraction analyses and confirmed to be single-phase compounds. The molar enthalpies of solution of these compounds have been measured at 298.15 K using an isoperibol calorimeter and the respective values at infinite dilution, Δ sol H m α (298.15 K), for the compounds Li 2 MoO 4 (c), Li 2 Mo 2 O 7 (c), Li 2 Mo 3 O 10 (c) and Li 2 Mo 4 O 13 (c) are −(33.88 ± 0.51), −(97.68 ± 0.52), −(167.20 ± 0.30) and −(247.68 ± 0.88) kJ mol −1 respectively. These data were used to calculate the standard molar enthalpies of formation Δ f H m o (298.15 K) and the respective values for the compounds are −(1520.13 ± 0.94), −(2279.29 ± 1.76), −(3032.68 ± 2.53) and −(3775.26 ± 3.46) kJ mol −1 . The results are compared with the available data in the literature.

The molar enthalpies of solution of ThMo 2 O 8 , Mo, and ThF 4 in (10 mol dm −3 HF(aq) + 4.41 mol dm −3 H 2 O 2 (aq)) have been measured using an isoperibol calorimeter. From these results and other auxiliary data, the standard molar enthalpy of formation of ThMo 2 O 8 has been calculated to be Δ f H m 0 (298.15 K) = (−2742.2 ± 4.5) kJ mol −1 . This value of enthalpy of formation of ThMo 2 O 8 is consistent with the second law enthalpy of formation of ThMo 2 O 8 determined in this laboratory by transpiration technique.

The enthalpies of solution of crystalline AlCl 3 and KBr were measured successively in one portion of 3.5 mol dm −3 HCl solution as well as AlBr 3 and KCl in another. The measurements were carried out in a 100 cm 3 reaction vessel of the isoperibol calorimeter LKB-8700. The standard enthalpy of the resulting reaction: A l C l 3 ( c ) + 3 K B r ( c ) = A l B r 3 ( c ) + 3 K C l ( c ) , was found to be Δ H r o ( 298.15 K ) = ( 6 3 . 4 ± 1 . 3 ) k J m o l - 1 which leads to Δ H f o ( A l B r 3 , c , 2 9 8 . 1 5 K ) = ( - 5 1 2 . 6 ± 1 . 9 ) k J m o l - 1 . The same measurements were carried out for AlCl 3 and KI and for AlI 3 and KCl. The standard enthalpy of the reaction: A l C l 3 ( c ) + 3 K I ( c ) = A l I 3 ( c ) + 3 K C l ( c ) , was found to be Δ H r o ( 298.15 K ) = ( 8 0 . 1 ± 1 . 4 ) k J m o l - 1 which leads to Δ H f o ( A l I 3 , c , 2 9 8 . 1 5 K ) = ( - 3 0 2 . 9 ± 2. 0 ) k J m o l - 1 .

The heats of formation in the Y- Pb system have been measured by using a differential direct isoperibol calorimeter. Compositions and the state of the samples were checked by chemical, metallographic and X-ray analyses. The following values (kcal/g-at.) were obtained for the various compounds (reaction in the solid state, ΔH300K): Y 5 Pb 3 : ΔH = −16.0 ± 0.5; Y 5 Pb 4 : ΔH = −14.4 ± 0.5 YPb 2 : ΔH = − 8.9 ± 0.5; YPb 3 : ΔH = − 6.7 ± 0.5 . These data have been compared with those obtained for the La-Pb and Y-Bi alloys and are discussed briefly in relation to the model suggested by Miedema (J. Less-Common Metals, 32 (1973) 117).

The enthalpies of the reactions of Zr(cr), ZrCl 1.09 (cr), and ZrCl 4 (cr) with (1.0HF + 2.9HCl) mol · dm −3 solution were measured in 0.1 dm 3 reaction vessel of the isoperibol calorimeter LKB-8700. The following standard molar enthalpies of formation were calculated: Δ f H m o (298.15 K)/(kJ · mol −1 ): ZrCl 1.09 (cr), −330.5 ± 2.4; ZrCl(cr), −303.2 ± 3.4; ZrCl 2 (cr), −531.0 ± 5.0; ZrCl 4 (cr), −980.7 ± 1.0. Heat-capacity measurements between 9 and 315 K were performed on pure samples of ZrCl 0.98 (cr) and ZrCl 4 (cr). The following standard molar thermodynamic quantities of crystal zirconium chlorides are reported at T ′ = 298.15 K: ZrCl ZrCl 2 ZrCl 4 C p, m o (T′)/( J · K −1 · mol −1 ) 47.26 ± 0.10 75 116.80 ± 0.20 S m o (T′)/( J · K −1 · mol −1 ) 60.94 ± 0.12 100 180.40 ± 0.35 “H m o (T′) − H m o (0)’/(J · mol −1 ) 9324 ± 10 14200 24590 ± 50 Δ f G m o (T′)/( kJ · mol −1 ) −276.5 ± 3.4 −482.7 ± 5.0 −889.9 ± 1.0

Heats of formation in the Dy-Bi system have been measured using a small furnace isoperibol calorimeter. The composition and states of the alloys were checked by chemical, metallographic and X-ray analyses. For the Dy-Bi compounds the following values were obtained for reaction in the solid state at 300 K: Dy 5+ x Bi 3 , ΔH = −19.5 ± 0.5 kcal (g atom) −1 ( x = 0); DyBi, ΔH = −23.0 ± 0.5 kcal (g atom) −1 . The results obtained are compared with those of other rare earth bismuthides and are discussed briefly.

Heats of formation in the Nd-Sb system were measured using a differential direct isoperibol calorimeter. The composition and state of the samples were checked by chemical, metallographic and X-ray analysis. The following values (±0.5 kcal (g atom)−1) of ΔHform were obtained for the various compounds (reaction in the solid state at 300 K): Nd5Sb3, −25.75; Nd4Sb3, −27.2; NdSb, −29.4; NdSb2, −21.7. These data have been compared with those previously obtained for the Nd-Bi systems and correlated, using the Miedema relationship, with the data for several bismuthides and antimonides.

Literature values of the enthalpy of formation of perchlorate ion are based solely on measurements of the enthalpy of decomposition of crystalline perchlorates and are in poor agreement. In this paper a new method—measurements of the enthalpies of reaction in solution—was used. The enthalpies of reduction of crystalline KClO4 and KBrO3 by TiCl3 solution were measured in the 100 cm3 reaction vessel of LKB-8700 isoperibol calorimeter. The enthalpies of solution of crystalline KCl and KBr were measured similarly in the same solution. The values ΔHfo(KClO4, c, 298.15 K) = − (431.41 ± 0.87) kJ mol−1, and ΔHfo(ClO4−, aq, 298.15 K) = − (127.79 ± 0.86) kJ mol−1, were calculated from appropriate thermochemical cycles.

The enthalpies of solution of α-Zr(SO 4 ) 2 (c), Zr(SO 4 ) 2 ·4H 2 O(c), ZrCl 4 (c), KCl(c), K 2 SO 4 (c), and H 2 O(l) in 3.0 mol·dm −3 HCl(aq) were measured. The measurements were carried out in the 100 cm 3 reaction vessel of the isoperibol calorimeter LKB-8700. The following values were calculated from these measurements: Δ f H m o {α-Zr(SO 4 ) 2 , c, 298.15 K) = −(2244.2 ± 2.2) kJ·mol −1 ; Δ f H m o {Zr(SO 4 ) 2 ·4H 2 O, c, 298.15 K} = −(3469.3 ± 2.7) kJ·mol −1 . α-Zr(SO 4 ) 2 includes an excess of 0.03 mol of SO 3 and in this paper α-Zr(SO 4 ) 2 means Zr(SO 4 ) 2 ·0.03SO 3 . Using literature enthalpies of solution of Zr(SO 4 ) 2 (c) and of its mono- and tetra-hydrates in water, the value: Δ f H m o {Zr(SO 4 ) 2 ·H 2 O, c, 298.15 K} = −(2576±6) kJ·mol −1 was calculated.

The heats of formation in the Ce-Sb system were measured using a direct isoperibol calorimeter. The composition and the equilibrium state of the samples were checked by metallographic and X-ray analyses. The following values were found for the various compounds (±0.5 kcal (g atom) −1 ) (reaction in the solid state at 300 K): Ce 2 Sb, −24.6; Ce 5 Sb 3 , −26.0; Ce 4 Sb 3 −27.9; CeSb, −30.2; CeSb 2 , −21.5. The results obtained are discussed briefly and are compared with those already known for other rare earth antimonides.

In the Y—Bi system the formation heats were measured using a direct isoperibol calorimeter. The following values were found for the two known compounds

The enthalpy of oxidation of NaNO2(aq) and KI(c) by K2Cr2O7 in 1 mol·dm−3 H2SO4 solution was measured in a 0.1 dm3 reaction vessel of the isoperibol calorimeter LKB-8700. The enthalpy of the reaction: NaNO2(sln, 43.64H2O)+I2(c)+H2O(l)+K2SO4(c)=NaNO3(c)+2KI(c)+H2SO4(sln, 53.40H2O), was found to be ΔrHmo(298.15 K) = (52.06±0.68) kJ·mol−1, which leads to ΔfHmo(NO2−1,aq,298.15 K) = −(100.0±0.9) kJ·mol−1.

In the PrBi system the heats of formation were measured using a direct isoperibol calorimeter. The composition and equilibrium state of the samples have been checked by chemical, metallographic and X-ray analyses. The following values were found for the two known compounds (reaction in the solid state, 300 K): The results obtained, compared with those already achieved in other REBi systems, are briefly discussed.

In the LaPb system the heats of formation were measured, using a differential direct isoperibol calorimeter, and checking composition and state of the samples by chemical, metallographic and X-ray analyses. For the various compounds the H (for the reaction among solid phases at 300 K) correspond to the following values (Kcal/g · at.): La5Pb3 = −17.25 ± 0.5, La4Pb3 = −16.7 ± 0.5, La5Pb4 = −16.5 ± 0.5, La3Pb4 = −15.3 ± 0.5, LaPb2 = −14.4 ± 0.5, LaPb3 = −13.7 ± 0.5. The results obtained are briefly discussed and compared with those calculated using the method suggested by MIEDEMA. Bildungswarmen von Lanthan-Blei-Legierungen Die Bildungswarmen von Lanthan—Blei-Legierungen wurden mittels eines Differentialcalorimeters gemessen sowie Zusammensetzung und Zustand der Proben durch chemische, metallographische und Rontgen-Analyse uberpruft. Fur die verschiedenen Verbindungen wurde Δ H (bei Reaktion der festen Phasen bei 300°K) bestimmt (Werte: s. „Abstract”). Die Ergebnisse werden kurz diskutiert und mit den nach der Methode von MIEDEMA berechneten verglichen.

A cursory re-examination of the Ce-Sn system was carried out using metallographic and X-ray analyses. The existence of the following phases was observed or confirmed: Ce3Sn, α-Ce5Sn3, β-Ce5Sn3, Ce5Sn4, Ce11Sn10 (approximate formula), Ce3Sn5 (approximate formula), Ce3Sn7, Ce2Sn5 and CeSn3. The lattice parameters of selected compounds were measured. The heats of formation of a number of Ce-Sn alloys were determined using a direct isoperibol calorimeter and the following values (kcal (g atom) −1) were found: Ce3Sn, −11.8 ± 0.5; Ce5Sn3, −17.5 ± 1.0; Ce5Sn4, −20.0 ± 1.0; Ce3Sn5, −18.0 ± 1.0; CeSn3, −14.0 ± 0.5. The results obtained are discussed briefly and are compared with those already known for other rare earth alloys with p-block elements.

An investigation on Bi-Th alloys was performed using X-ray and metallographic analyses and measurements of the heats of formation. The crystal structures of Th3Bi4 (c128, Th3P4 type) and ThBi2(tP6, Cu2Sb type) were confirmed; moreover two phases with an hP16, Mn5Si3-type structure and a cP2, CsCl-type structure respectively were observed. The ΔH of formation of Th-Bi alloys was measured using a direct isoperibol calorimeter. The following values were obtained for the various compounds (reaction in the solid state at 300 K): Th5Bi3, −15.9 ± 0.5 kcal (g atom)1; ThBi, −19.4 ± 0.5 kcal (g atom)1; Th3Bi4, −20.4 ± 0.5 kcal (g atom)1; ThBi2, −16.5 ± 0.5 kcal (g atom)1. The data available (both the results obtained in this work and those already known) are discussed briefly and related to a possible shape of the phase diagram.

The general alloying behaviour of tin with the rare earths was summarized on the base of the available literature data. A re-examination of the LaSn alloys has been performed using x-ray and metallographic analyses. The existence of the following phases has been observed or confirmed: . The formation heats of the LaSn alloys have been measured using a direct isoperibol calorimeter. The values of ΔHform (solid alloys, room temperature, K cal/g atom) are the following: . A re-examination of the YSn alloys has been also carried out confirming the existence and the crystal structures of the following phases: Y5Sn3, Y5Sn4, Y11Sn10, YSn2 and YSn3. A few calorimetric measurements performed on selected Sn-rich alloys have given the following values of the ΔHform: YSn2 (−15.5 ± 1.0 Kcal/g atom), YSn3 (−12.5 ± 0.5 Kcal/g atom). The results obtained are discussed briefly and are compared with the data available for other rare earth-tin alloys. Beitrag zum Legierungsverhalten der Seltenen Erden mit Zinn Literaturubersicht uber das allgemeine Legierungsverhalten des Zinns mit den Seltenen Erden. Rontgenographisch und metallographisch wurde das System LaSn nochmals uberpruft; beobachtet bzw. bestatigt wurden die Phasen . Die Bildungswarmen der LaSn-Legierungen wurden calorimetrisch bestimmt. Bildungsenthalpien ΔH (feste Legierungen, Raumtemperatur, Kcal/g-Atom): . Die Uberprufung des Systems YSn bestatigte die Existenz und Struktur von Y5Sn3, Y5Sn4, Y11Sn10, YSn2 und YSn3. Bildungsenthalpien ΔH einiger Sn-reicher Legierungen: YSn2 −15,5 ± 1,0 Kcal/g-atom; YSn3 −12,5 ± 0,5 Kcal/g-Atom. Die Ergebnisse werden diskutiert und mit den Werten anderer Legierungen von Seltenen Erden mit Zinn verglichen.

The enthalpies of formation of solid nickel—zinc alloys have been measured at 355 K using an isoperibol calorimeter and the technique of tin-solution calorimetry, and values have been obtained for the nickel-rich α-solid solutions and for the β1, γ, γ1 and δ intermediate phases. Exothermic values have been observed throughout and these have been compared with the results obtained in previous free energy studies and with those suggested by the empirical model of Miedema. The existing free energy data have been re-assessed at 900 K and the results combined with the present calorimetric enthalpies to derive entropies of formation. The possible contributions to the entropies of the phases are discussed and their Debye temperatures are estimated.

Heats of formation in the La-In system have been measured using a differential direct isoperibol calorimeter. The compositions and states of the alloys were checked by chemical, metallographic and X-ray analyses. For LaIn3 (reaction in the solid state, 300 K), ΔH = −14.0 ± l kcal (g atom)−1 was obtained. For alloys near the equiatomic composition, values between −15 and −16 kcal (g atom)−1 were obtained.

The heats of formation of Gd—Bi alloys were measured using a direct isoperibol calorimeter. The composition and equilibrium state of the samples were checked by metallographic and X-ray analyses. The following values were found for the different compounds [Δ H form, reaction in the solid state, 300 K, kcal (g-atom) −1 ± 0.5]: Gd 5+ x Bi 3 , −20.0 ± 0.7; Gd 5 Bi 3 , −20.9; Gd 4 Bi 3 , −22.0; GdBi, −23.1. The results obtained were compared with those already achieved for other rare earth bismuthides.

A recently constructed isoperibol calorimeter has been modified to measure the spontaneous reactions of Li2O, Na2O, CaO, and BaO with As2O5 after ignition. Thus, the heats of formation from the component oxides have been determined for Li3AsO4, Na3AsO4, Ca3As2O8, and Ba3As2O8.

A recently constructed isoperibol calorimeter has been modified to measure the spontaneous reactions of Li2O, Na2O, CaO, and BaO with As2O5 after ignition. Thus, the heats of formation from the component oxides have been determined for Li3AsO4, Na3AsO4, Ca3As2O8, and Ba3As2O8.

The heats of formation of the Y-Sb system have been,measured using a differential direct isoperibol calorimeter. The following values (kcal (g atom) −1 ) were obtained for the various compounds (reaction in the solid state at 300 K): Y 3 Sb, ΔH from = −15.3 ± 0.5; Y 5 Sb 3 , ΔH from . = −23.0 ± 0.5; YSb, ΔH from . = −25.0 ± 0.5. The composition and state of the samples were checked by chemical, metallographic and X-ray analyses. The data have been compared with those obtained for the Y-Bi and Nd-Sb systems and discussed briefly.

Heats of formation in the LaSb system have been measured using a small furnace isoperibol calorimeter. The compositions and states of the alloys prepared in the calorimeter were checked by metallographic and X-ray analyses. The following values of ΔH form (kcal ( g atom) −1 ± 0.5) were obtained for the various compounds, for reaction in the solid state at 300 K: La 2 Sb, −23.4; La 5 Sb 3 , −25.5; La 4 Sb 3 , −28.4; LaSb, −31.2; LaSb 2 , −22.0. The experimental data are discussed briefly and found to be in good agreement with those computed according to Miedema's model and, for the La-rich alloys, also with those calculated according to Kubaschewski's suggestion based on the effective coordination number.