New humidity sensor material (CaSO4.2H2O)0.975-(CuSO4•5H2O)0.025

We have prepared composite samples of citrogypsum (calcium sulfate) dihydrate (CaSO4 center dot 2H(2)O) doped with copper sulfate (CuSO4 center dot 5H(2)O). The morphology of the microsection surface and the energy dispersive X-ray spectrum (EDX) of the sample were examined. The conductivity of the samples was studied by impedance spectroscopy. To measure the conductivity, an RLC AM-3026 AKTAKOM meter was used in the frequency range of 200 Hz - 5 MHz with an alternating signal amplitude of 1 V without DC polarization. The measurements were carried out at a constant temperature of 28 degrees C and relative humidity in the range from 30 to 90%. The frequency dependences of complex resistance and relative permittivity on relative humidity, total complex, active and reactive resistances are measured. We demonstrated the possibility of practical application of (CaSO4 center dot 2H(2)O)(0.975)-(CuSO4 center dot 5H(2)O)(0.025) as a new air humidity sensor material. The new air humidity sensor material was obtained from a waste of the citric acid production.