In order to study the effect of Zr doping on the thermoelectric properties of p-type Bi10.17Sb30.72 Zr0.35Te58.28Se0.48 single crystal, ?n ingot was prepared by Bridgman method. Cut and cleaved samples from different regions of ingot were characterized by a Hall Effect based on the Van der Pauw method. The first measurements were conducted with four ohmic contacts at room temperature and the obtained results were presented in our investigation, earlier. ?lso, high charge carriers mobility was obtained on the sample with silver contacts at the temperature of liquid nitrogen. Single crystal was characterized by Seebeck coefficient (S), conductivity (?) and resistivity (?) measurements as ? function of temperature in the range of 40-320?C by a home-made impedance meter. The prepared single crystal has a figure of merit (Z) of 1.22 x 10-3 K-1 at 300?C.

El lingote del mono cristal de BiSbTeSe dopado con Zr se sintetizó utilizando el método de Bridgman. La composición química se determinó mediante análisis con espectroscopía de dispersión de energía (EDS). Mediante difracción de rayos X (DRX) se demostró que el lingote de cristal obtenido es un mono cristal y confirmó que se trata de un compuesto del tipo Bi2Te3, con orientación del mono cristal (001). El punto de fusión se determinó por medidas dilatométricas. La movilidad, concentración, resistividad/conductividad, y el coeficiente de Hall del BiSbTeSe dopado con Zr, se determinaron utilizando un sistema de medición de efecto Hall basado en el método de Van der Pauw. El efecto Hall se midió a temperatura ambiente con una intensidad de campo magnético aplicada de 0,37 T a diferentes intensidades de corriente. Las muestras de lingotes medidos se cortaron y se rompieron de diferentes regiones. Las muestras de lingotes utilizadas en las medidas fueron obtenbidas mediante corte y escisión en distintas zonas. Los resultados obtenidos utilizando un sistema de medición de efecto Hall (Ecopia, HMS-3000) en las distintas muestras, se compararon entre sí. Los resultados confirmaron que las propiedades eléctricas y de transporte del mono cristal dependen de la dirección del crecimiento del cristal. La movilidad se mejoró significativamente en comparación no solo con el valor teórico de Bi2Te3 sino también con los datos existentes en la literatura.

As part of research on the influence of selenium as dopant on bismuth telluride, a successful synthesis of single crystal was carried out. Single crystal of p type conductivity, with the given compound formula, Bi2Te2.88Se0.12, was obtained by the Bridgman process. The obtained empirical formula does not deviate from the given compound formula. Single crystal was characterized by Hall Effect system based on the Van der Pauw method. Also, bulk sample was characterized by Seebeck coefficient (S), thermal conductivity (?) and electrical resistivity (?) measurements, as ? function of temperature in the range of 40-320?C by ? homemade impedance meter. The prepared single crystal has a figure of merit (Z) of 2.16 x 10-3 K-1 at 40?C. Values of ZT are about 1.0 at 27?C for commercialized p and n type of bismuth telluride ingots. T is absolute temperature.

Thermoelectric materials are attracting attention because of their ability to directly convert heat into electricity. Bismuth tellurides (Bi₂Te₃) are important thermoelectric materials used to convert heat into electricity and vice versa. The application of thermoelectric devices requires materials that exhibit superior thermoelectric performance. This work investigates the thermoelectric properties of Bi 2Te 2.7Se 0.3 single crystal synthesized via Bridgman method by spontaneous nucleation. The Seebeck coefficient (S) is negative, which means that this crystal has electrons as the main charge carriers. The Seebeck coefficient values range from -163 mV·K⁻¹ at 300°C to -188 mV·K⁻¹ at 40°C. As part of research on the influence of selenium as dopant on bismuth telluride, a successful synthesis of n type single crystal was carried out. The Bi 2Te 2.7Se 0.3 single crystal in 11 mm × 80 mm size was grown. The obtained empirical formula does not deviate from the given compound formula. The single crystal was characterized by measurements of Seebeck coefficient (S), conductivity (c) and resistivity (r) measurements as a function of temperature in the range of 40-320°C by a home-made impedance meter. The prepared single crystal exhibited a figure of merit (Z) of 1.77 x 10-3 K-1 at 300°C. Figure of merit was calculated using measured values for resistivity, Seebeck coefficient and conductivity.

The Bi0.5As1.5Te2.98Se0.02 single crystal in 11 mm?80 mm size was grown using the Bridgman method. Energy dispersive spectrometry (EDS) analysis was used to determine the chemical composition of the studied samples, as well as for checking and confirming the homogeneity of the samples. Mobility, concentration of charge majority carriers and Hall coefficient of single crystal, were determined using a Hall Effec system based on the Van der Pauw method. Hall Effect was measured at room temperature with four ohmic contacts and at temperature of liquid nitrogen with silver contacts with an applied magnetic field strength of 0.37 T at different current intensities. The expected improvement in the mobility of obtained single crystal doped with this content of arsenic was not obtained.

The subject of this paper is validation the analytical method of determining the content of heavy metals Al, As, Cd, Cu, Fe, Mn, Ni, Pb i Zn in water using the mass spectrometry with inductively coupled plasma. The validation parameters that were studied are: linearity, limit of detection (LoD), limit of quantification (LoQ), recovery and precision (RSD). For determined analytes, the values of validation parameters were: LoD (0.011-2.23) mg/L, LoQ (0.03 - 3.4) mg/L, recovery (above 96 %) and the RSD (0.9-3.1) %.