TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Method: In producing the joined product, the specific temperature is lower than the sintering temperature of the ceramic member. The thermal coefficient of expansion (TCE) of the ceramic member is in the range of 5-25x 10-6/ degrees C, preferably 8-17x 10-6/ degrees C; and/or where the TCE of the further member is 5-25x 10-6/ degrees C, preferably 8-17x 10-6/ degrees C; and/or where the coefficient of thermal expansion (CTE) of the glass layer or glass-ceramic layer is 6-16x 10-6/ degrees C, preferably 11-13x 10-6/ degrees C, where the CTE is determined by dilatometry measurement. The ceramic member is an oxide ceramic that shows a perovskite structure, which is preferably selected from CaTi1-xFexO3 (0 less than or equal to x less than or equal to 1, preferably 0.75 less than or equal to x less than or equal to 0.95), Ba1-xSrxCo1-yFeyO3 (0 less than or equal to x less than or equal to 1, preferably 0.25 less than or equal to x less than or equal to 0.75; and 0 less than or equal to y less than or equal to 1, preferably 0.25 less than or equal to y less than or equal to 0.75), La1-xSrxCoO3 (0 less than or equal to x less than or equal to 1, preferably 0.25 less than or equal to x less than or equal to 0.75), La1-xSrxCo1-yFeyO3 (0 less than or equal to x less than or equal to 1, preferably 0.20 less than or equal to x less than or equal to 0.65 and 0 less than or equal to y less than or equal to 1, preferably 0.6 less than or equal to y less than or equal to 0.9), and which is more preferably selected from CaTi0.9Fe0.1O3 (CTF), Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF), La0.5Sr0.5CoO3 (LSC) and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), and/or where the ceramic member comprises a non-perovskite metal oxide, preferably magnesium oxide (MgO). The further member is made of a material selected from ceramics, metals, metal-alloys, cermets, or semiconductor materials, preferably metals such as steel. The joined product is a tubular oxygen membrane joined to a steel pipe. The glass or a glass-ceramic layer is formed of a glass composition, comprising 5-70 mol% calcium oxide (CaO), 5-45 mol% zinc oxide (ZnO), 5-50 mol% boron oxide (B2O3) 1-85 mol% silicon dioxide (SiO2), based on the total glass composition. The glass composition comprises 25-60 mol%, preferably 45-50 mol% CaO; and/or 10-35 mol%, preferably 17.5-25 mol% ZnO; and/or 10-40 mol%, preferably 17.5-25 mol% B2O3; and/or 2.5-45 mol%, preferably 7.5-15 mol% SiO2. The glass composition comprises 35 mol% or less, preferably 10 mol% or less MgO; and/or 35 mol% or less, preferably 10 mol% or less aluminum oxide (Al2O3). The glass composition comprises 30 mol% or less, preferably 10 mol% or less sodium oxide (Na2O); and/or 30 mol% or less, preferably 10 mol% or less MgO. Furthermore, the glass composition comprises one or more compounds of the group, comprising lanthanum oxide (La2O3), yttrium oxide (Y2O3), lead oxide (PbO), chromium oxide (Cr2O3), vanadium oxide (V2O5), nickel oxide (NiO), copper oxide (CuO), titanium dioxide (TiO2), zirconium dioxide (ZrO2), arsenic oxide (As2O3), antimony oxide (Sb2O3), iron oxide (Fe2O3), strontium oxide (SrO), and barium oxide (BaO), preferably in a total amount of 5 mol% or less. The reaction layer forms a gradient of at least one physical or chemical parameter, which is different in the ceramic member and the glass or glass-ceramic composition, in a way that the difference in the parameter is gradually equalized. The parameter is selected from the CTE and the concentration of at least one component of the ceramic member and/or the glass or glass-ceramic composition.