Link: https://www.amazon.co.jp/dp/B07F9Y8P97/ref=cm_sw_r_tw_awdo_c_x_xeSqBbEHBF135
Spoiler(read only if you have read the VN) Track 27 from CD 2 is titled >!Luka's death!<
I've never been able to find an official source for the OG Steins;Gate Anime OST.
But, here's a listing for the CD of the Steins;Gate 0 Anime OST: https://www.amazon.co.jp/dp/B07F9Y8P97