Searches for B0 decays to ηK0, ηη, η′η′, ηϕ, and η′ϕ

We search for B0 meson decays into two-body combinations of K0, η, η′, and ϕ mesons in 324×106 BB̅ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We measure the following branching fractions (upper limits at 90% confidence level) in units of 10-6: B(B0→ηK0)=1.8-0.6+0.7±0.1(<2.9), B(B0→ηη)=1.1-0.4+0.5±0.1(<1.8), B(B0→ηϕ)=0.1±0.2±0.1(<0.6), B(B0→η′ϕ)=0.2-0.3+0.4±0.1(<1.0), and B(B0→η′η′)=1.0-0.6+0.8±0.1(<2.4), where the first error is statistical and the second systematic.