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Sb2 − xBixTe3 (x = 0.43–0.51) thermoelectric materials were prepared by the powder metallurgy method. The effects of grinding and sintering processes on the Seebeck coefficient, electrical conductivity, and thermoelectric figure of merit were investigated. For different particle sizes, a shift in maximum of Z = f(x) dependence was found. This shift can be explained by the presence of point defects and their interaction. Cold-pressed material with Z ~ 3.1 × 10−3 K−1 was prepared.

ERYTHROCYTES, when suspended in blood plasma, form ‘rouleaux’, in which the single erythrocytes lie parallel like a pile of coins. This phenomenon is dependent on the presence of a specific substance in the plasma. When suspended in an isotonic sugar solution, the erythrocytes settle to the bottom very slowly, without forming any characteristically shaped aggregation. On the other hand, the same suspension of blood cells, when exposed to the influence of a powerful electric field (approximately 100 V./cm.), rapidly forms macroscopically visible aggregations of red blood cells, quickly settling to the bottom. In this way, all erythrocytes are separated from the supernatant sugar solution in a few minutes.

Reflectance in the infrared region and lattice parameters were measured on Bi2+xTe3 and Bi2+xSe3 single crystals. The plasma resonance frequency, N m> tT and P m tT , respectively, were determ The process of incorporation of the superstoichiometric Bi is discussed from the changes of the optical and lattice parameters and by means of quantum-chemical calculation. Two possible ways of incorporation are considered: (i) forming anti-site defects Bi'Se(Te) and (ii) forming seven-layer or nine-layer lamellae. It appears that at the lower concentrations of superstoichiometric bismuth there exist anti-site defects of the Bi'Te or Bi'Se type, whereas upon increasing the content of Bi atoms in the lattice of these chalcogenides could lead to the formation of seven-layer or nine-layer lamellae.

Presuming constant Seebeck coefficient, specific heat and electric conductivity, equations were derived which describe the connections of quantities such as temperature, cooling power, electric current, dimensions and shape of a cooling thermoelement.

The concentration of holes in InxBi2−xTe3 crystals for x = 0.0–01 has been determined using simplified assumptions on the basis of experimental values of the transport coefficients. These data and the calculated changes of bonding parameters were used to formulate more precisely the idea of the variation of the concentration of antisite defects in mixed crystals with increasing indium concentration. The obtained results have been employed in proposing a model that makes possible a generalization on the relations among structure, bonding, and concentration of antisite defects in AIIIxBV2−xCVI3 crystals. In agreement with the model it has been shown that the increasing content of In or Tl atoms results in an increase in the ratio c a of the lattice parameters, in a decrease of the unit cell volume, in an increase of the electron density in the outer atomic planes of the layer, and in a decrease of the concentration of both the antisite defects and the free carriers.

The aim of this letter is to report the preparation of Sb2Te3-Sb2Teg_xSx and Sb2Te3-Sb2Te3_xS~ monocrystalline structures. Contrary to all expectations, p -n junctions 'were observed on these structures. Similar problems were discussed previously [1] for Bi2Te3-Bi2Se3 system. Samples with a concentration gradient of Se and S, respectively, were prepared from Sb2Te3 single crystals. Sb2Te3 single crystals were grown using the Bridgman method in conical quartz ampoules. The starting elements of semiconductor purity (99.999%) in the stoichiometric ratio were synthesized at a temperature of 1073 K for 48 h. Ampoules charged with synthesized polycrystalline material were lowered into t]~e temperature gradient of 400 K (5 cm) -I at a rate of 1.3 mmh -t. Single crystals obtained, approximately 60 mm long and 10 mm in diameter, were used to prepare the samples of dimensions 10 mm x 10 mm x 2 ram. The cleavage planes of single crystals formed the larger-area sides of the samples. The samples prepared in this way were annealed in S and Se vapour, respectively, at 623 K for 50 h. After annealing, the samples were cleaved into halves along the {0 0 0 1) planes. The resultant samples in plate-like form were of dimensions 10 m m x 10 m m x 1 mm, having higher concentration of S and Se, respectively, in one side of the sample. The concentration profiles of the samples were measured perpendicularly to the {0 0 0 1 ) planes by means of an energy-dispersive X-ray (EDX) microanalyser (KEVEX; Fig. 1). It follows from Fig. 1 that Se atoms diffuse into Sb2Te3 crystals relatively easily and form there an area of mixed crystal. This is in agreement with the phase diagram of the Sb2Teg-Sb2Se3 system [2]. The Sb atoms needed for the formation of a compound is probably taken from SbTe point defects. Therefore, the crystal volume increases. The process can be expressed by the equation

Reflectance and transmittance in the IR spectral range are investigated on Sb2−xInxTe3 (x = 0.00 to 0.37) single crystal samples grown by a modified Bridgman method. By fitting the reflectance spectra the values of the plasma resonance frequency ωp, optical relaxation time τ, and high-frequency dielectric constant e∞are determined. With increasing indium concentration in the samples these quantities decrease from the values ωp = 1.88 × 1014 s−1, τ = 2.4 × 10−14 s, and e∞ = 55 for x = 0.00 down to the values ωp = 0.81 × 1014 s−1, τ = 0.8 × 10−14 s, and e∞ = 41 for x = 0.37. The observed variations are qualitatively accounted for by interaction of substitutional In defects arising on building of In atoms into the Sb2Te3 lattice with anti-site Sb defects. The transmittance curves permit to determine the dependence of the absorption coefficient x on incident photon energy. The change in the width of the optical gap with increasing In concentration in the samples is discussed. The values of the exponent α in the relation x ∼ λα for the long-wavelength absorption edge drop from 2.5 for Sb2Te3 to 1.2 for Sb1.63In0.37Te3. An den Proben von 2−xInxTe3-Einkristallen (x = 0,00 bis 0,37), dargestellt nach der modifizierten Bridgman-Methode, werden Reflektivitat und Transmission im IR-Bereich ermittelt. Durch das Anpassen der Reflexionsspektren werden die Werte der Plasma-Resonanzfrequenz ωp, der optischen Relaxationszeit τ und der Hochfrequenz-Dielektrizitatskonstante e∞ bestimmt. Mit zunehmender Indium-Konzentration sinken in den Proben die angegebenen Grosen von ωp = 1,88 × 1014 s−1, τ = 2.4 × 10−14 s und e∞ = 55 fur x = 0,00 zu Werten ωp = 0,81 × 1014 s−1, τ = 0,8 × 10−14 s und e∞ = 41 fur x = 0,37. Die beobachteten Veranderungen werden qualitativ durch Wechselwirkung der im Sb2Te3-Gitter entstehenden Substitutionsstorstellen In, mit Antistrukturdefekten Sb erklart. Aus dem Verlauf der Transmission wird die Abhangigkeit des Absorptionskoeffizienten x von der Energie einfallender Photonen ermittelt. Die Veranderung der optischen Breite der Bandlucke mit zunehmender In-Konzentration in den Proben wird diskutiert. Die ermittelten Werte des Exponenten α aus der Relation x ∼ δα fur die langwellige Absorptionskante sinken von 2,5 fur Sb2Te3 zu 1,2 fur Sb1.63In0.37Te3.

The value of the Hall constant RH(B ∥ c) is determined for single crystalline Sb2−xInxTe3(x = 0.00 to 0.37) and Sb2Te3−xSex (x = 0.00 to 1.25) samples prepared by means of the Bridgman method; it is found that the concentration of free carriers (holes) decreases with increasing value of x. This effect is accounted for by interaction of substitutional In or Se defects with anti-site Sb′Te defects of the Sb2Te3 crystal lattice; the resulting In or Se defects increase the bond polarity of the crystal lattice – higher crystal ionicity results in a suppression of the concentration of anti-site defects. Invoking the changes in bonding parameters obtained from a quantum-chemical calculation, we explain the fact that the In defects suppress the concentration of antisite defects considerably, whereas the suppression of the Sb′Te concentration due to the formation of Se defects is substantially lower. The results indicate that the Se atoms entering the TeII sites in the Sb2Te3 crystal affect the bond polarity only slightly whereas the change in polarity due to indium entering the cation sublattice of Sb2Te3 is substantially higher. Es wird die Hall-Konstante RH(B ∥ c) fur einkristalline Bridgman-Proben von Sb2−xInxTe3 (x = 0,00 bis 0,37) und Sb2Te3−xSex(x = 0,00 bis 1,25) bestimmt. Die Konzentration freier Trager (Locher) nimmt mit wachsendem x ab. Dies wird auf die Wechselwirkung von substitionellen In- und Se-Defekten mit Sb′Te-Antisite-Defekten des Sb2Te3-Kristallgitters zuruckgefuhrt. Die In- und Se-Defekte bewirken eine Erhohung der Bindungspolaritat des Kristallgitters – eine hohere Ionizitat fuhrt zu einer Abnahme der Konzentration von Antisite-Defekten. Unter Verwendung der Ergebnisse quantenmechanischer Rechnungen zur Anderung der Bindungsparameter kann die starke Abnahme der Antisite-Defekte durch die In-Defekten erklart werden, dagegen ist die Abnahme der Sb′Te-Konzentration infolge Bildung von Se-Defekten erheblich geringer. Diese Ergebnisse zeigen, das Se-Atome, die die TeII-Platze im Sb2Te3-Gitter einnehmen, die Bindungspolaritat nur schwach beeinflussen, wahrend die Anderung der Bindungspolaritat infolge Besetzung von Kationenplatzen im Sb2Te3 durch Indium erheblich hoher ist.

Using the results of the Hall constant and the electrical conductivity measurements of Bi2−xInxTe3 single crystals, the decrease of free carrier concentration with the increasing value of x is determined. In anticipation of one antisite defect BiTe′ producing one hole in the crystal lattice and on the grounds of considerations about the bond polarity and the energy of formation of antisite defects, the influence of In-atoms on the free carrier concentration is explained. The value of formation energy for four values of x is calculated. The considerations about the changes of bond polarity with the increasing value of x are supported by quantum chemical calculations which also serve to explain the changes of lattice parameters with the increasing content of built-in In atoms. Mit den Ergebnissen von Messungen der Hallkonstante und des elektrischen Widerstands von Bi2−xInxTe3-Einkristallen wird die Abnahme der Konzentration freier Trager mit steigendem x bestimmt. Da ein Antiplatzdefekt BiTe′ ein Loch im Kristallgitter hervorruft und auf Grund von Betrachtungen uber die Bindungspolaritat und Bindungsergie von Antiplatzdefekten wird der Einflus von In-Atomen auf die Konzentration freier Trager erklart. Der Wert der Bildungsenergie fur vier Werte von x wird berechnet. Die Betrachtungen uber die Anderunge der Bindungspolaritat mit steigendem Wert von x werden durch quantenchemischen Rechnungen bestatigt, die auch dazu dienen, die Anderungen der Gitterparameter mit steigendem Gehalt der eingebauten In-Atome zu erklaren.

Single crystals of Sb2-xInxTe3 (x = 0.0-0.4) were prepared from the elements of 5N purity using the modified Bridgman method. On the samples with a various content of incorporated In-atoms the optical properties (reflectivity, transmission) in IR region and the transport coefficients (electrical conductivity σ⊥c, Hall coefficient RH(B || c), Seebeck coefficient S⊥c) were measured. The results showed that the In-atoms incorporated in Sb2Te3 crystal lattice suppress the free carrier concentration. The observed decrease in the hole concentration with increasing content of incorporated In-atoms was explained by the interaction of incorporated In-atoms with antisite defects Sb'Te. The increasing concentration of incorporated In-atoms in the crystal lattice leads to the increase of the bond polarity and to the increase of ionicity of the studied mixed crystals. The consequence of these changes is the decrease of antisite defect concentration.

Reflectivity has been measured in the region of plasma resonance frequency on strongly doped n-Bi2Te3(I) crystals with a free electron concentration of 2×10 to 3×26m−3. Using some simplifying conditions, given in this work, and the values of electrical conductivity, Hall and Seebeck coefficients, we have carried out the interpretation of the reflection spectra; it has turned out that for the description of the conduction band a model based on the idea of the existence of light and heavy electrons with a value of splitting factorΔ′=C·025 cV is more suitable than the non-parabolic model. The values of the effective massm⊥1 in the direction perpendicular to the trigonal axisc may be found for the specimens being measured in the interval 0·07–0·15m0. They indicate that the subband corresponding to light electrons exhibits deviations from the paraboiicity. The value ofm⊥2, determined according to the described procedure, seems to be constant; thus, in a first approximation, the band corresponding to heavy electrons is parabolic.

Sb2Te3 single crystals are synthetized doped with germanium in the concentration range up to 13%. The lattice parameters of these crystals are measured and found to show anomalous behaviour in the range of low Ge concentrations. On the basis of changes observed in the bonding parameters and using the variations of the plasma resonance frequency values of the crystals with Ge content, the anomalous behaviour of the lattice parameters is accounted for as a consequence of the interaction of anti-site Sb′Te defects with Ge atoms built into the lattice. Mit Germanium im Konzentrationsbereich bis zu 13% dotierte Sb2Te-Einkristalle werden synthetisiert. Die Gitterparameter dieser Kristalle werden gemessen und ein anomales Verhalten im Bereich niedriger Ge-Konzentrationen gefunden. Auf der Grundlage der beobachteten Anderungen der Bindungsparameter und mit der Variation der Plasmaresonanzfrequenz des Kristalls mit dem Ge-Gehalt, wird das anomale Verhalten der Gitterparameter als Folge der Wechselwirkung von Antiplatz-Sb'Te-Defekten mit in das Gitter eingebauten Ge-Atomen erklart.

A quantum chemical calculation of bonding parameters in Sb2Te3, Bi2Te3, Bi2−xInxTe3, and Bi2Te3−xSx single crystals is carried out. The electric conductivity σ ⟂ c and Hall constant RH(B ∥ c) of the crystals in the Bi2Tes−xSx system are measured. These results present a basis for the discussion of the different role of impurities in anion and cation sublattices with respect to the bonding parameters and the concentration of anti-site defects in the Bi2Te3−xSx system is calculated and compared with the formation energy of the same defects in the Bi2−xInxTe3 system. Es wird eine quantenchemische Berechnung der Bindungsparameter in Sb2Te3-, Bi2Te3-, Bi2−xInxTe3- und Bi2Te3−xSx-Einkristallen durchgefuhrt. Die elektrische Leitfahigkeit σ ⟂ c und die Hallkonstante RH(B ∥ c) der Kristalle im Bi2Te3−xSx-System werden gemessen. Diese Ergebnisse ergeben eine Grundlage fur die Diskussion der unterschiedlichen Rolle der Storstellen im Anionen- und Kationensubgitter bezuglich der Bindungsparameter und es wird die Konzentration der Anti-Platzdefekte im Bi2Te3−xSx-System berechnet und mit der Bildungsenergie derselben Defekte m Bi2−xInxTe3-System verglichen.

Information is given on a long-term observation of gMT activities in the blood of cattle, aimed at using the results to interpret metabolic tests, especially tests of the function of liver. Dynamics of changes in the gMT activities was studied in the year seasons and the per cent activities in the decades (from 20 to 100 U per 1) in different groups of cows according to their reproduction cycle. In the part discussion relationships are given between the gMT activities and other findings obtained from metabolic tests. The average value of the gMT activities in the blood of a reference group of cows was 30.7 U per 1. The standard deviation was 7.01 U per 1. Reference limits for the gMT activities in the bovine blood serum - 16.7 to 44.7 U per 1 (95% interval of confidence) could be determined by a parametric statistical method. Average deviations of the gMT activities from those in the reference group of cows, expressed in histogram units J, ranged from 0.03 to 1.07 J after a long-term observation in particular calendar months. The maximum positive deviations were observed in January, June, July, November and they indicate the risk period, in August and September the values nearly approached those in the reference group of cows. The maximum positive deviation of the metabolic test amounted to 6.8 J (January). There were eight metabolic tests with the deviation greater than 1 J during the observation, two in the summer period (May--October) and six in the winter period (November-April). In cows after calving and in the first half of gravidity the gMT activities were most frequently in the decade 30.5-40.0 U per 1, and in highly pregnant cows in the decade 20.5-30.0 U per 1.

The study was aimed at informing about the results of metabolic trials in large cattle stocks for the period from 1977 to 1980, particularly in view of the dynamics of changes in different metabolic parameters in each year season. The histogram method of statistical evaluation was used. Attention is drawn to the prevailing risk factors in each season and it is possible to investigate the general trend of the rise of new metabolic disorders, or suppression of older ones, in large cattle stocks. The risk metabolic factors of each season can be derived from the results. The summer season is characterized by the tendency to metabolic and respiratory acidosis, by the highest elimination of calcium combined with potassium stress, and by a lack of sodium ions. In the autumn the animals show a more pronounced form of metabolic and respiratory acidosis, not always sufficiently compensated; the liver is overloaded, there is a tendency to hypocalcaemia, and ketosis occurs more frequently, often very pronounced. In winter the acid-base balance of blood improved, acidosis is compensated more intensively by the renal route, calcium is increasingly eliminated in the urine, the overload on liver function is at its maximum, and ketosis occurs most frequently. The spring findings included increased elimination of calcium with the urine, the lowest Ca X P product over the whole year (this is in a high correlation with the higher activities of the ALP enzyme). the highest load of nitrogen compounds and worsened haemogenesis. It can be stated that the mentioned results represent some improvement in the metabolic profile as compared with earlier studies. The situation in enzyme activities can be regarded as a factor of deterioration: high activities of alkaline phosphatase documenting a tension in the metabolism of calcium and phosphorus, and increasing occurrence of chronical overloading of liver function, particularly in winter.

The aim of the study was to compare the acid-base (AB-) findings in cattle obtained parallelly by the equilibration method after Astrup and the partial method (titration determination of total carbon dioxide in blood plasma) and at the same time to determine pH, net acid-base exudate in urine and the specific weight of urine. Altogether we made 65 parallel examinations in three groups of cows according to phases of reproduction. In 70.8% of cases correlation between the two results was very good or good, however under the condition that in many cases it was necessary to know also blood pH for the employment of the partial method. Without the knowledge of the blood pH good correlation would be obtained only in 33.8% of all cases. The partial method does not provide satisfactory results mainly in diagnosing respiratory disturbances and in determining compensatory degree of acid-base disturbances. We analysed two alternative values for the top, reference limit of vol. % CO2 in plasma: 60.0 or 55.0. The results imply that from the aspect of correct partial method interpretation it is more accurate to use the value 60.0. A high interpretation correlation between pH and net acid-base urine exudate was also confirmed and that independent urine pH values may be used in a complex acid-base examination to obtain acid-base findings. The representation of the basic types of acid-base disturbances indicates that metabolical acidoses are most frequent in highly pregnant cows (36.9%) mostly without proved compensation. The largest proportion of normal acid-base findings (43.4%) was determined in cows after calving in which also the compensatory mechanisms were most often activated. In connection with these findings the possibilities of impaired health of calves are discussed.