interested on a sabbatical leave vs interested in a sabbatical leave

Some examples from the web:

• The Vice Dean's away on a sabbatical.
• So, you're going on a sabbatical.
• He told me he's currently on a sabbatical, traveling the world and thinking about what he could do next in life.
• Is he can be on a sabbatical, even when he's with someone.
• I'm still on a sabbatical from work, so I spend the bulk of my day at home with the... children.
• Five years ago, I was on a sabbatical, and I returned to the medical university where I studied.
• You know, like the time kept passing, and we were on a sabbatical.
• We're going on a sabbatical so we can really improve our French.
• But what you didn't know was that the professor was on a sabbatical, which is why he caught you trying to kill Skinner.
• That's why he's on a sabbatical in south America right now.
• What would I do on a sabbatical?
• But now she's on a sabbatical, she can experience the world.
• And after the supposed "theft," he went on a sabbatical from work for two weeks and returned to work with bruises and a broken ankle.
• The only thing he could do, really, was take a year off telling everybody he was on a sabbatical.
• Since 2011, he is on a sabbatical year and is carrying out his ministry in various parishes in Obala. (SL) (Agenzia Fides 28/5/2012)
• The professor is in Japan on sabbatical leave.
• Subject: Sabbatical leave for Council staff
• Subject: Further question on sabbatical leave in the Commission
• In 2002 a head of division at the Commission was apparently granted three years' sabbatical leave to work for a large, US-based software company.
• Your whole life is a sabbatical.

Some examples from the web:

• The professor is in Japan on sabbatical leave.
• Subject: Sabbatical leave for Council staff
• Subject: Further question on sabbatical leave in the Commission
• In 2002 a head of division at the Commission was apparently granted three years' sabbatical leave to work for a large, US-based software company.
• Your whole life is a sabbatical.
• long-term paid absences such as long-service leave or sabbatical leave;
• If sabbatical leave is granted, what is the basis for it in the Staff Regulations?
• I've decided to allow Jo a sabbatical.
• Leslie, you need to take a sabbatical.
• You need to take a sabbatical.
• I now officially insist that you take a sabbatical.
• I've decided to allow Jo a sabbatical.
• I talked her into taking a sabbatical from the university.
• He says I should take a year off, a sabbatical.
• Not permanently, just a sabbatical.
• He was granted a sabbatical in 1968 to pursue post-graduate studies in archaeology.
• In France, taking a sabbatical has become a right.
• In 1955 Pollock spent a sabbatical in Ajijic a small village on Lake Chapala in Mexico.
• We need a sabbatical year to discover them all: one perday.
• I heard you took a sabbatical from school.